Method and device for determining parameters affecting ship infrared characteristics

Abstract

The present invention relates to a method and device for determining parameters influencing the infrared characteristics of a ship. The method comprises: pre-establishing a relationship equation between effective infrared radiation data of each facet on a ship target, multiple environmental parameters, and multiple parameters to be determined; obtaining n*m groups of test data for the corresponding facet of the ship target in an actual scenario; inputting each m groups of test data into the relationship equation to obtain a group of nonlinear constraint equations with multiple parameters to be determined as variables; solving each group of nonlinear constraint equations using the Newton method to obtain a corresponding group of estimated values ​​of the parameters to be determined; calculating a confidence interval for each parameter to be determined based on the n groups of estimated values ​​of the parameters to be determined, determining the estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of each parameter to be determined, and determining the target value corresponding to the parameter to be determined based on the estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of the parameter to be determined. The present invention can improve the accuracy of the parameters to be determined.

Description

Technical Field

[0001] The present invention relates to the technical field of ship infrared characteristic research, and in particular to a method and device for determining ship infrared characteristic influencing parameters. Background Art

[0002] The complexity and variability of the infrared characteristics of maritime ship targets in real-world naval battlefield environments presents one of the primary challenges in studying their infrared characteristics. Firstly, the infrared characteristics of ship targets are extrinsic and strongly coupled to their surrounding environment. In reality, the infrared characteristics of ship targets are not only related to the target's inherent properties (e.g., surface infrared emissivity, reflectivity, area, and geometric structure), but also depend on its surface temperature (which in turn is determined by internal heat sources, ambient air temperature, wind speed, wind direction, and solar radiation). These characteristics are also closely related to the surrounding sea and sky infrared background radiation and atmospheric transmission effects. Secondly, for non-cooperative ship targets, standard methods only allow for simple dimensions and photographic data. Key information such as thermal boundary conditions, infrared physical properties, and dynamic conditions is difficult to obtain, making infrared characteristic research even more challenging. Even for cooperative ship targets, due to the uncontrollable nature of marine environmental conditions, the deviation in the measurement of the ship's own physical parameters, and the changes in surface radiation characteristics caused by use, the research object of the ship's infrared characteristics will be in a certain "non-cooperative" state, making it difficult to evaluate its infrared characteristics through simple simulation modeling, experimental testing, and other means. Summary of the Invention

[0003] In order to solve the above technical problem or at least partially solve the above technical problem, the present invention provides a method and device for determining parameters affecting infrared characteristics of a ship.

[0004] In a first aspect, the present invention provides a method for determining parameters affecting infrared characteristics of a ship, comprising:

[0005] Establish in advance the relationship equations between the effective infrared radiation data of each facet on the ship target, multiple environmental parameters and multiple parameters to be determined;

[0006] Obtaining n*m sets of test data corresponding to the bin of the ship target in an actual scene; wherein each set of test data includes apparent infrared radiation data of a corresponding pixel point of the ship target in the thermal imager and corresponding multiple environmental parameters, m is the number of the parameters to be determined, and n is a positive integer greater than 1;

[0007] Inputting each m groups of test data into the relational equation to obtain a group of nonlinear constraint equations with the multiple parameters to be determined as variables, and solving each group of nonlinear constraint equations using Newton's method to obtain a corresponding group of estimated values ​​of the parameters to be determined; wherein each group of estimated values ​​of the parameters to be determined includes an estimated value of each parameter to be determined, and n*m groups of test data correspond to n groups of estimated values ​​of the parameters to be determined;

[0008] Based on the n groups of estimated values ​​of the parameters to be determined, the confidence interval of each parameter to be determined is calculated, the estimated value that falls within the corresponding confidence interval among the n estimated values ​​of each parameter to be determined is determined, and the target value corresponding to the parameter to be determined is determined based on the estimated value that falls within the corresponding confidence interval among the n estimated values ​​of each parameter to be determined.

[0009] In a second aspect, the present invention provides a device for determining parameters affecting infrared characteristics of a ship, comprising:

[0010] The equation pre-building module is used to pre-establish the relationship equations between the effective infrared radiation data of each facet on the ship target, multiple environmental parameters and multiple parameters to be determined;

[0011] a data acquisition module, configured to acquire n*m ​​groups of test data corresponding to the bin of the ship target in an actual scene; wherein each group of test data includes the apparent infrared radiation data of the corresponding pixel point of the ship target in the thermal imager and a plurality of corresponding environmental parameters, where m is the number of parameters to be determined, and n is a positive integer greater than 1;

[0012] an equation solving module, configured to input each m groups of test data into the relational equation to obtain a group of nonlinear constraint equations with the multiple parameters to be determined as variables, and solve each group of nonlinear constraint equations using Newton's method to obtain a corresponding group of estimated values ​​of the parameters to be determined; wherein each group of estimated values ​​of the parameters to be determined includes an estimated value of each parameter to be determined, and n*m groups of test data correspond to n groups of estimated values ​​of the parameters to be determined;

[0013] The interval screening module is used to calculate the confidence interval of each parameter to be determined based on the n groups of estimated values ​​of the parameter to be determined, determine the estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of the parameter to be determined, and determine the target value corresponding to the parameter to be determined based on the estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of the parameter to be determined.

[0014] The method and apparatus for determining parameters affecting ship infrared characteristics provided in this embodiment first establish a relationship equation between the effective infrared radiation data of each bin, multiple environmental parameters, and multiple parameters to be determined. Then, n*m sets of test data are obtained and input into the relationship equation to obtain n estimated values ​​for each parameter to be determined. A corresponding confidence interval is then calculated for each parameter to be determined, and reasonable estimated values ​​are screened based on the confidence intervals. Finally, a target value for the parameter to be determined is determined based on the screened estimated values. In other words, the relationship equation in the present invention can reflect a relationship model for the mutual coupling between the ship target and the environment. Then, real test data (including apparent infrared radiation data from a thermal imager and environmental parameters) is collected and input into the relationship equation, resulting in a constraint equation with the parameters to be determined as variables. After solving the constraint equation, the calculated estimated values ​​are screened by calculating confidence intervals, and the final target value is determined based on the screened estimated values. Thus, the present invention, based on infrared radiation theory, establishes a relationship equation for the coupling between the target and the environmental background, and obtains a target value at a certain confidence level, effectively addressing the problem of inaccurate infrared characteristic modeling and simulation calculations for non-cooperative targets. That is, the present invention studies the mechanism of the infrared radiation characteristics of ship targets, forms a parameterized theoretical model of the mutual coupling between ship targets and the sea and sky environment, and combines measured data to carry out inversion technology research on the parameters to be determined of non-cooperative targets, so as to solve the problem of "untrue simulation" of the infrared characteristics of ship targets under complex marine environment conditions, that is, to improve the accuracy of the parameters to be determined, thereby further improving the simulation degree of the infrared characteristics of ship targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0017] Figure 1 1 is a flow chart of a method for determining parameters affecting infrared characteristics of a ship according to an embodiment of the present invention;

[0018] Figure 2 Schematic diagram of the transmission path of the infrared signal when a ship target is detected by an infrared thermal imager in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0020] In a first aspect, the present invention provides a method for determining the influencing parameters of the infrared characteristics of a ship, such as Figure 1 As shown, the method includes:

[0021] S100, pre-establishing a relationship equation between the effective infrared radiation data of each facet on the ship target, multiple environmental parameters, and multiple parameters to be determined;

[0022] According to thermal radiation theory, any object with a temperature above absolute zero will emit radiation energy in the form of thermal radiation. The radiation energy emitted by targets such as ships and sea surfaces in the infrared band forms their observable infrared characteristics. Figure 2 As shown in the figure, the infrared thermal image recorded by infrared thermal imagers and other measuring equipment is the infrared radiation emitted by a target with a certain temperature. After multiple reflections and absorptions between the target and the environmental background, the infrared signal is attenuated by the atmospheric transmission effect.

[0023] When constructing the above relationship equation, factors such as atmospheric transmission effect, infrared scene coupling between target and background, and the formation mechanism of target temperature field need to be considered. These factors are introduced one by one below.

[0024] (1) Atmospheric transmission effect

[0025] The atmosphere (especially the humid air near the sea surface) is not completely transparent in the infrared band. Therefore, the thermal image observed by the thermal imager is actually the infrared brightness distribution of the target and background in the viewfinder after being transmitted through the atmosphere. Assuming that the thermal imager is an ideal instrument, that is, the thermal imager is perfectly calibrated and there is no measurement error, the observed infrared brightness is the sum of the target's transmitted radiation after atmospheric attenuation and the path radiation of the atmospheric path. Specifically, it can be expressed as the following formula (1):

[0026] L obv，i (R) = τ ir (R, T air )L app，i +[1-τ ir (R, T air )]L b (T air ) (1)

[0027] The meaning of each parameter in formula (1): L obv，iis the infrared brightness value corresponding to a certain pixel point i in the thermal imager, in units of W / (m2sr), that is, the apparent infrared radiation corresponding to the i-th pixel point on the thermal imager; R is the distance between the i-th surface element of the target surface corresponding to the i-th pixel point and the thermal imager, in units of m; τ ir is the transmittance of the atmosphere in the working band of the thermal imager; T air is the atmospheric temperature, in K; L app，i L is the apparent infrared brightness of the target surface corresponding to the i-th pixel on the thermal imager without atmospheric attenuation, in W / (m2sr), that is, the effective infrared radiation of the i-th surface element; b (T air ) is the infrared brightness of blackbody radiation at atmospheric temperature, with the unit of W / (m2sr).

[0028] Obviously, L app，i L obv，i It can better represent the infrared characteristics of the target itself, so when inverting infrared characteristics, we should first try to eliminate the influence of atmospheric transmission on the measurement results. air After obtaining R, the atmospheric transmittance τ can be calculated according to atmospheric transmission models such as ModTran. ir , thereby eliminating the influence of atmospheric transmission and obtaining effective infrared radiation.

[0029] (2) Infrared scene coupling between target and background

[0030] Considering the coupling effect of the radiation field, the effective radiation of the i-th surface element is composed of the emission radiation of the i-th surface element itself, the effective radiation of the i-th surface element to other hull surface elements, and the reflection components of the sea surface background radiation, sky background radiation and solar radiation. For details, please refer to the following formula (2):

[0031]

[0032] The meaning of each parameter in formula (2): ε ir is the infrared emissivity of the target surface within the working band of the thermal imager; T i is the thermodynamic temperature of the i-th surface element on the target, in K; G i，ship is the input radiation from other ship elements to the i-th element, in W / (m2sr); G i，sea is the input radiation from the sea surface radiation source to the i-th surface element, in W / (m2sr); G i，sky is the input radiation from the sky radiation source to the i-th surface element, in W / (m2sr), G i，sun is the input radiation from the solar radiation source to the i-th surface element, in W / (m2sr); F i，j is the radiation angle coefficient from the i-th to the j-th surface element; Fi，sky is the radiation angle coefficient from the i-th surface element to the sky hemisphere; F i，sea is the radiation angle coefficient from the ith surface element to the sea surface; L sky is the sky background radiation brightness, unit is W / (m2sr); L sea is the sea surface radiance, unit is W / (m2sr); E sun is direct solar radiation, unit is W / m2; θ i is the angle between the normal vector of the ith surface element and the direction of the sun.

[0033] Obviously, the emitted radiation ε of the target surface ir L b (T i ) than L app，i It can better represent the essential characteristics of the target. Therefore, when inverting infrared characteristics, we should try to decouple the radiation field from the apparent radiation L app，i Separate the purer target emission radiation ε ir L b (T i ) quantity.

[0034] (3) Target temperature field

[0035] Because the above formula (2) involves the thermodynamic temperature of the surface element, different calculation methods can be used for surface elements at different positions. The following lists several temperature calculation methods for surface elements.

[0036] (3.1) The temperature field of the hull is determined by the thermodynamic differential equations that control its temperature field and its boundary conditions. There is no internal heat source in the hull steel plate. Therefore, for any point in the hull steel plate that is not on the boundary, the temperature field satisfies the following differential equation, that is, formula (3):

[0037]

[0038] The meaning of each parameter in formula (3): λ is the thermal conductivity of the hull steel plate, ρ is the density of the hull steel plate, the unit is kg / m 3 ; c is the specific heat of the hull steel plate, unit is kJ / kg℃.

[0039] (3.2) There is convective heat transfer between the inner wall of the hull and the airflow in the cabin. For any point on the inner wall of the cabin, the temperature field satisfies the following differential equation, that is, formula (4):

[0040]

[0041] The meaning of each parameter in formula (4): λ is the thermal conductivity of the steel plate of the hull, T in is the cabin air temperature, λ isois the thermal conductivity of the insulation layer, in W / (m℃); D iso is the thickness of the insulation layer, in m; h in is the convective heat transfer coefficient in the cabin.

[0042] (3.3) There is convective heat transfer between the outer wall of the hull and the airflow outside the cabin, and there is also radiative heat transfer between the ambient environment and the sun. For any point on the outer wall of the cabin, its temperature field satisfies the following differential equation, namely, formula (5):

[0043]

[0044] The meaning of each parameter in formula (5): λ is the thermal conductivity of the steel plate of the hull, h out is the external flow field convection heat transfer coefficient, unit is W / (m 2 ℃); D is the thickness of the hull steel plate, in m; T air is the air temperature around the hull, in °C; Q rd is the radiation heat transfer between the hull surface and the environment, in W / m 2 .

[0045] In order to accurately describe the changing law of the hull temperature field, the radiation heat transfer is divided into two parts: solar band radiation heat transfer and normal temperature band radiation heat transfer. The radiation heat transfer Q rd It can be expressed as the following formula (6):

[0046]

[0047] The meaning of each parameter in formula (6): is the direct solar radiation intensity, in W / m 2 ; is the solar diffuse irradiance, in W / m 2 ;E sky is the sky hemispheric radiance, in W / m 2 ; ε is the radiation emissivity of the surface element at room temperature; F sky is the radiation angle coefficient from the surface element to the sky hemisphere; E sea is the sea surface radiation emittance, in W / m 2 ; F sea is the radiation angle coefficient from the surface element to the sea surface; α is the radiation absorption rate in the visible light band; T is the thermal field temperature of the surface element. If the surface element is the i-th surface element, then T is T i ; θ is the angle between the normal vector of the surface element and the direction of the sun. If the surface element is the i-th surface element, then θ is θ i ;σ is the Stefan-Boltzmann constant.

[0048] It can be seen that the above formulas (3) to (6) constitute a complete set of differential equations describing the hull temperature field, from which the temperature of any point on the hull at any time can be determined.

[0049] Based on the above analysis, the general process of constructing the relationship equation includes:

[0050] First, the atmospheric transmission effect is corrected: the thermal imager records the infrared signal after atmospheric transmission on the observation path, also known as apparent radiation. The apparent radiation observed by the thermal imager consists of two parts: the effective radiation of the ship target after atmospheric transmission and the path radiation on the atmospheric path. The first step in inverting the infrared characteristics of the ship is to eliminate the influence of the atmospheric transmission effect, and obtain the "effective radiation" of the ship at zero distance without atmospheric transmission from the measured apparent radiation infrared thermal image. If the optical resolution of the infrared thermal imager used in the actual detection measurement is p*q, the infrared thermal image of the ship can be regarded as a dot matrix composed of p*q pixels, and the infrared brightness signal recorded by each pixel has experienced the atmospheric radiation transmission on the corresponding observation path. Based on the above formula (1), for any pixel i of the ship target in the infrared thermal image, its effective radiation L at zero distance is app，i It can be expressed as formula (7):

[0051]

[0052] As mentioned above, the atmospheric transmittance τ can be determined by field measurements or by calculation based on field measurement parameters. ir , temperature T air Parameters such as, then according to formula (7) we can get the apparent radiation brightness L recorded by the thermal image obv，i Correcting the influence of atmospheric transmission effect, the effective radiation brightness L at zero distance is obtained app，i .

[0053] It is understandable that after correcting the atmospheric transmission effect, the effective radiation shell of each area on the ship under zero-distance conditions can be obtained from the actual detection thermal image.

[0054] In most cases, the detection of non-cooperative targets at sea is carried out by reconnaissance ships or sea platforms such as islands and reefs. In fact, the thermal images are usually taken at a near-horizontal angle of view. At a near-horizontal angle of view, the main radiation surface of the ship is the outermost wall of the hull and superstructure (such as the side of the ship). These walls usually do not have a complex radiation exchange relationship with other walls of the hull, that is, F i，j = 0. In this case, based on the above formula (3), the expression of the effective radiation of the i-th surface element after removing the infrared radiation coupling effect can be established:

[0055]

[0056] For any surface element i on the hull, its temperature T i It is determined by its internal and external thermal boundary conditions and the thermal properties of the hull material. When the non-cooperative ship target is in a stable navigation state, it can be approximately considered that the hull is in a steady-state thermal equilibrium state. According to the law of conservation of energy, for any surface element i, refer to the following formula (9):

[0057] Q cv，i +Q in，i +Q rd，i +Q cd，i =0 (9)

[0058] For the outer wall of the ship, except for some areas with thermal boundary conditions or sudden changes in geometric shape, the temperature gradient on the hull surface is close to 0 in the thermal equilibrium state, and the transverse heat conduction (i.e., heat conduction along the hull direction) can be ignored, that is, refer to the following formula (10):

[0059] Q cd，i =0 (10)

[0060] The calculation of external heat transfer heat flow can be referred to the following formula (11):

[0061] Q cv，i =h out (T air -T i ) (11)

[0062] The calculation of internal heat conduction heat flow can be referred to the following formula (12):

[0063]

[0064] The calculation of radiation heat transfer heat flux can be referred to the following formula (13):

[0065]

[0066] The above formulas (9) to (13) can be sorted out into the following formula (14):

[0067]

[0068]

[0069] Among them, H in is the comprehensive heat transfer coefficient of the heat source in the cabin, see the following formula (15)

[0070]

[0071] The following formula (16) is known:

[0072]

[0073] After sorting out the above formulas (8), (14), and (16), we can obtain the following formula (17):

[0074]

[0075] The above formula (17) involves multiple influencing parameters, specifically including environmental parameters and intrinsic parameters. Some of these parameters can be obtained by measurement or calculation, and some parameters are parameters required to be solved by the present invention. Some of the parameters involved in the above formula are summarized below. The summary results are shown in Table 1 below:

[0076] Table 1 Summary of influencing parameters

[0077]

[0078]

[0079] From the perspective of the type of influencing parameters, they can be divided into two categories:

[0080] (1) Ship's intrinsic parameters

[0081] These influencing variables are bound to the target ship. For a given ship, the values ​​of the intrinsic parameters remain constant. That is, for the same target, the values ​​of the intrinsic parameter variables remain the same in infrared thermal images taken under different operating conditions. Therefore, once the values ​​of the intrinsic parameters are determined, they can be treated as fixed constants. Those that cannot be immediately determined can be treated as "unsolved parameters" and solved using mathematical inversion methods using real-world data.

[0082] (2) Environmental parameters

[0083] These influencing parameters vary with the specific environmental conditions during infrared thermal imaging, such as weather, sea conditions, and navigation. If these influencing variables can be measured simultaneously during thermal imaging, or if there are reliable empirical formulas or physical models that can estimate them based on measurable quantities, they can be treated as constants to reduce the complexity of the problem. Otherwise, they need to be treated as independent varying dimensions.

[0084] The influencing parameters are described in detail below:

[0085] (1) Environmental parameters

[0086] (1.1) Sky radiance L in the thermal imager's operating band sky，ir

[0087] Similar to direct solar radiation, L sky，ir It is mainly determined by the ambient atmospheric conditions and is a typical environmental variable. This parameter can be measured synchronously when recording thermal images.

[0088] (1.2) The sea surface radiation brightness L in the thermal imager working band sea，ir

[0089] L sea，ir It is determined by sea surface waves (usually determined by sea surface wind speed), surface sea temperature, seawater refractive index (seawater refractive index is related to salinity), etc., and is a typical environmental variable; sky，ir Similar, L sea，ir It is also possible to perform simultaneous measurements while recording thermal images.

[0090] (1.3) Outside air temperature T air

[0091] Temperature, especially in open, unobstructed areas like the ocean, typically varies on a geographic scale, with negligible variations over distances of several kilometers. Therefore, the temperature around the camera can be used as a proxy for the atmospheric temperature around a non-cooperative target.

[0092] (1.4) Direct solar radiation intensity E sun_dir

[0093] For surface ships, solar radiation is the primary external heat source during the day, significantly impacting the ship's infrared field. The intensity of direct solar radiation is determined by factors such as the Earth-Sun relationship, date and time, latitude and longitude, and local weather conditions, making it a typical environmental variable. For accuracy and reliability, on-site measurements should be used whenever possible.

[0094] (1.5) Solar diffuse irradiance E sun_dif

[0095] Like direct solar radiation intensity, diffuse solar radiation is also a typical environmental variable and can be measured using specialized meteorological instruments.

[0096] (1.6) Sky hemispheric irradiance E sky

[0097] Hemispherical sky radiation is the radiant illumination of the entire sky hemisphere on the horizontal ground in the thermal radiation band (3μm to 50μm). It is a typical environmental variable. Hemispherical sky radiation can be accurately measured using specialized meteorological instruments such as a pyrheliometer.

[0098] (1.7) Sea surface radiation emittance E sea

[0099] From the perspective of radiative heat transfer, the sea surface that exchanges radiation with the ship's hull is primarily the surface surrounding the ship. Within this radiation angle range, the sea surface can be treated as a gray body. Therefore, simply measuring the sea surface temperature (or the blackbody radiation temperature of the sea surface at a near-perpendicular angle in the longwave band) allows for a relatively accurate estimation of the sea surface's radiative emittance.

[0100] (1.8) Atmospheric transmittance τ on the observation path ir

[0101] τ ir It refers to the ability of the atmospheric path between the thermal imager and the target to transmit infrared signals in the working band of the thermal imager when shooting infrared thermal images. Obviously, τ ir It is related to the positional relationship between the target and the photographer when recording the thermal image, and the environmental meteorological conditions at the time of shooting (relative humidity, air pressure, concentration of radioactive gas components, aerosol particle size and concentration distribution, etc.), and is a typical environmental variable. τ can be obtained by measuring under the same sea conditions and calculating and converting it. ir There are two specific methods for obtaining this parameter:

[0102] The first is direct measurement. Place a standard object around the infrared camera and record the target. By measuring the atmospheric transmittance along the path to the standard object, the transmittance of the non-cooperative target can be calculated.

[0103] The second is indirect measurement. When shooting infrared thermal images, the atmospheric environmental parameters such as temperature, humidity, air pressure, and visibility are measured simultaneously. The atmospheric transmittance of the target is then calculated using empirical formulas or theoretical models (such as Modtran).

[0104] (1.9) Direct solar radiation E in the thermal imager working band sun，ir

[0105] E sun，ir It is determined by the distance between the earth and the sun, the solar pitch angle and azimuth angle at the test site, and the atmospheric profile (the distribution of parameters such as radiant gases, aerosol concentration, and temperature that affect atmospheric transmission along the thickness of the atmosphere, which is closely related to seasons and regions). It is a typical environmental variable. Modtran and other radiation transmission calculation software can be used to calculate E based on input parameters such as date, time, longitude and latitude. sun，ir The direct solar radiation in the visible light band can also be measured by the solar radiation meter, and the infrared band E can be converted through the empirical formula. sun，ir .

[0106] (1.10) Surface convection heat transfer coefficient h out

[0107] The surface convection heat transfer coefficient is mainly determined by the incoming wind speed, wind direction, and geometric shape. Among them, the geometric shape of the ship is a fixed value, but the incoming wind speed and wind direction vary with the ambient wind speed and direction, the ship's speed and heading, etc. Therefore, the surface convection heat transfer coefficient is also an environmental variable. For non-cooperative targets, although it is impossible to directly measure their h out , but it can measure the wind speed and direction on site more accurately. According to the wind speed and direction parameters, h can be determined by experimental correlation or flow field simulation calculation. out , and more preferably, it is obtained by inversion using the method provided by the present invention.

[0108] (2) Intrinsic parameters

[0109] (2.1) Radiation angle coefficient of the surface element to the sky;

[0110] (2.2) Radiation angle coefficient of the surface element to the sea surface;

[0111] (2.3) Radiation angle coefficient between surface elements;

[0112] (2.4) The angle between the normal vector of the surface element and the direction of the sun;

[0113] The influencing variables in items (2.1) through (2.4) are all determined by the geometry of the ship's exterior surface. In item (2.4), the sun direction vector can be accurately calculated using the local latitude and longitude and the date and time. Therefore, item (2.4) is primarily determined by the direction of the bin normal vector, which is uniquely determined by the ship's exterior surface geometry. A ship's geometric structure remains largely unchanged after its final design and construction (though some ships may experience partial changes after modernization). Therefore, items (2.1) through (2.4) can be considered intrinsic parameters of the ship and are independent of external meteorological conditions.

[0114] (2.5) Absorption rate α of the hull surface in the visible light band;

[0115] (2.6) Radiative emissivity ε of the hull surface at normal temperature;

[0116] (2.7) Hull surface infrared emissivity ε ir ;

[0117] The three influencing variables (2.5) to (2.7) are radiation characteristic parameters determined by the ship's surface coating. Naval vessels typically have fixed coating requirements, using fixed formulations and color combinations. Therefore, these three variables can be considered intrinsic parameters of the ship and are largely unaffected by ambient weather conditions.

[0118] (2.8) Cabin temperature T in

[0119] The cabin temperature of a ship's cabin is primarily determined by the air conditioning setpoint or air supply temperature, as well as temperature variations caused by internal heat sources (e.g., heat from electronic equipment power, lighting, power equipment heat dissipation, and personnel load). Its value depends primarily on the cabin's design and internal heat load, and is largely unrelated to the meteorological environment. Therefore, cabin temperature can be considered an intrinsic parameter of the ship. in The temperature is mainly determined by the cabin's purpose. For example, cold storage and medical cabins have separate refrigeration equipment, and the cabin temperature is usually slightly lower than the air conditioning setpoint. Cabins such as the command cabin and bridge are well ventilated, and the temperature is usually about 1°C higher than the air conditioning setpoint. Areas such as the galley and power equipment compartments usually have a temperature about 10°C higher than the air supply temperature due to internal heat sources.

[0120] (2.9) Cabin convection heat transfer coefficient h in

[0121] With T in Similarly, the cabin convection heat transfer coefficient is primarily determined by cabin type and is an intrinsic parameter of the ship. Based on experience, for well-ventilated cabins such as the command and bridge compartments, the cabin convection heat transfer coefficient typically reaches around 10W / m²°C. For equipment compartments with less personnel activity and less ventilation, the cabin convection heat transfer coefficient is typically around 6W / m²°C. Based on experience, the cabin convection heat transfer coefficient can be preliminarily determined based on cabin type, and its precise value can be further calculated after other intrinsic parameters are determined.

[0122] (2.10) Steel plate thickness;

[0123] (2.11) Thermal conductivity of steel plate;

[0124] Steel plate thickness and thermal conductivity are primarily determined by the thermal properties of the hull material and are considered intrinsic parameters of the ship. Intelligence channels allow us to obtain the steel grade used in a ship, and thus roughly determine its density, thermal conductivity, specific heat capacity, and other physical properties.

[0125] (2.12) Thickness of thermal insulation layer;

[0126] (2.13) Thermal conductivity of insulation layer;

[0127] The thickness of the insulation layer and the thermal conductivity of the insulation layer are intrinsic parameters of the ship. Once the design and construction are completed, their values ​​will no longer change. A preliminary estimate can be made based on the experience of our military ships.

[0128] (2.14) Steel plate density;

[0129] (2.15) Specific heat capacity of steel plate;

[0130] Steel plate density and specific heat capacity are coefficients of the time-differential term in the temperature control equation. Their values ​​primarily influence the hull temperature distribution during dynamic processes. Under steady-state thermal equilibrium conditions, the time-differential term can be set to zero, and the steel plate density and specific heat capacity have no effect on the hull temperature distribution. If the target is under steady-state thermal equilibrium or at anchor during detection, it can be assumed to be in steady-state thermal equilibrium. In this case, the steel plate density and specific heat capacity do not affect the temperature distribution, and inversion is not required.

[0131] In summary, the above analysis and derivation are summarized as follows:

[0132] (1) The relational equation may include:

[0133]

[0134] Where ε is the radiation emissivity of the surface element at room temperature, ir is the infrared band emissivity of the hull surface, L app，i is the effective infrared radiation data of the i-th pixel on the thermal imager, L sea is the sea surface radiance, F i，sea is the radiation angle coefficient from the ith surface element to the sea surface, L sky is the sky background radiance, F i，sky is the radiation angle coefficient from the i-th surface element to the sky hemisphere, E sun is direct solar radiation, θ i is the angle between the normal vector of the ith element and the direction of the sun, h out is the external flow field convection heat transfer coefficient, h in is the cabin convection heat transfer coefficient, T i is the thermodynamic temperature of the i-th element, α is the radiation absorption rate in the visible light band, is the direct solar radiation intensity, is the solar scattered radiation illuminance, ε is the radiation emissivity in the normal temperature band, T in is the cabin air temperature, T air is the atmospheric temperature, E sky is the sky hemispheric radiance, E sea is the radiation emittance of the sea surface; the i-th pixel point of the thermal imager corresponds to the i-th surface element on the ship target, ε ir ,ε,α,h out 、h in and T in is the parameter to be determined, L sea 、F i，sea , L sky 、F i，sky 、E sun ,θ i 、 T air 、Esky and E sea For environmental parameters.

[0135] Among them, ε ir ,ε,α,h out 、h in and T in are the parameters to be determined, among which there are five parameters ε ir ,ε,α,h in and T in is the intrinsic parameter, a parameter h out are environmental parameters, most of the parameters to be determined are intrinsic parameters, and the remaining parameters can be obtained through measurement or calculation.

[0136] (2) Temperature calculation

[0137] The above formula (3) can be used as the first formula to solve the temperature of any point inside the hull steel plate that is not on the boundary, that is, the first formula is:

[0138]

[0139] Where λ is the thermal conductivity of the hull steel plate, ρ is the density of the hull steel plate, and c is the specific heat capacity of the hull steel plate.

[0140] The above formula (4) can be used as the second formula to solve the temperature of the inner wall surface of the hull. The second formula includes:

[0141]

[0142] Where λ is the thermal conductivity of the hull steel plate, iso is the thermal conductivity of the insulation layer, D iso is the thickness of the insulation layer.

[0143] The above formula (5) can be used as the third formula to solve the temperature of the outer wall of the hull. The third formula includes:

[0144]

[0145] Where λ is the thermal conductivity of the hull steel plate, D is the thickness of the hull steel plate, Q rd is the radiation heat transfer coefficient between the hull surface and the environment.

[0146] S200, obtaining n*m groups of test data corresponding to the bin of the ship target in an actual scene; wherein each group of test data includes apparent infrared radiation data of the corresponding pixel point of the ship target in the thermal imager and multiple environmental parameters, m is the number of the parameters to be determined, and n is a positive integer greater than 1;

[0147] It is understandable that if, when conducting non-cooperative target detection, the infrared thermal image of the target under certain working conditions has been recorded with high quality, and the relevant environmental parameters have been recorded simultaneously, then the target's unknown parameters can be inverted based on a small amount of actual detection data, laying the foundation for understanding the changing laws of the infrared characteristics of non-cooperative target ships.

[0148] For the first six environmental parameters in Table 1 above, relevant instruments and equipment can be used to measure them synchronously during non-cooperative target testing. In fact, meteorological parameters are often concepts with a geographical scale. Especially in marine environmental conditions, meteorological parameters usually do not change drastically within a few kilometers or even tens of kilometers. Therefore, under relatively stable meteorological conditions (no thunderstorms, non-stormy typhoon weather), meteorological parameter measurements can be carried out at the location of the measurement platform or on the shore around the test sea area. The seventh to ninth environmental parameters can be calculated based on the environmental parameters measured on-site during non-cooperative target testing.

[0149] It is understandable that the apparent infrared radiation data in each set of test data corresponds to the environmental parameters obtained through measurement or calculation.

[0150] S300, inputting each m groups of test data into the relational equation to obtain a group of nonlinear constraint equations with the multiple parameters to be determined as variables, and solving each group of nonlinear constraint equations using Newton's method to obtain a corresponding group of estimated values ​​of the parameters to be determined; each group of estimated values ​​of the parameters to be determined includes an estimated value of each parameter to be determined, and n*m groups of test data correspond to n groups of estimated values ​​of the parameters to be determined;

[0151] It is understandable that after substituting each 6 sets of test data, 6 nonlinear constraint equations are obtained, that is, a set of constraint equations. This set of constraint equations is about the parameter to be determined <ε ir >, <ε>, <α>, <h out 〉, <H in >, <T in > is a set of nonlinear constraint equations. For the convenience of description, the above parameters are simply denoted as x i ,i=1,2,...,n,n=6.

[0152] For example, by collecting 6 sets of test data under independent working conditions, each of which includes the apparent infrared radiation data of the corresponding pixel points in the thermal imager and multiple environmental parameters obtained by measurement or calculation, these 6 sets of test data are input into the relational equation to obtain a set of nonlinear constraint equations. After solving this set of nonlinear constraint equations, a set of estimated values ​​of the 6 parameters to be determined can be obtained, that is, a set of solutions.

[0153] Considering that certain measurement or calculation errors may occur during the acquisition of test data, these errors, when propagated, can affect the calculation results of the parameters to be determined. To eliminate these errors, more test data is usually required. That is, if n*m groups of test data are acquired in S200, where m is the number of parameters to be determined, and each m groups of test data yields a set of estimated values ​​for six parameters to be determined, then n*m groups of test data yield a total of n sets of estimated values ​​for six parameters to be determined.

[0154] In a specific implementation, the Newton method is used to solve each set of nonlinear constraint equations to obtain a corresponding set of estimated values ​​of parameters to be determined, which may include:

[0155] S1. Set the initial iteration vector formed by m parameters to be determined Let k = 0;

[0156] S2, let the nonlinear constraint equations be F(x), calculate F(x (0) );

[0157] S3, let A0=J(x (0) ), J(x (0) ) is F(x (0) ), calculate the Jacobian matrix of

[0158] S4. Calculation

[0159] S5. Calculate F(x (k+1) );

[0160] S6, let y k+1 =F(x (k+1) )-F(x (k) ), s k+1 =x (k+1) -x (k) ;

[0161] S7, command

[0162] S8, command

[0163] S9, judge ||x (k+2) -x (k+1) ||<e is true, e is a preset value close to 0; if so, exit the iteration process and set x (k+2) As the solution of the nonlinear constraint equations; otherwise, k=k+1, return to S5.

[0164] Among them, move one side of each constraint equation in the constraint equation group to the other side, so that all data are on one side and the other side is 0. At this time, the constraint equation group can be recorded as F(x). That is:

[0165] F=(f1,f2,...,f n ) T , f i =f(x1, x2, ..., x n ), i=1, 2,..., n, n=6

[0166] It can be seen that there are 6 constraint equations f in a set of equations F, and each constraint equation f is a nonlinear constraint equation with 6 parameters to be determined.

[0167] By using the Newton method, the constraint equations can be calculated to obtain a set of estimated values ​​for the m parameters to be determined.

[0168] S400. Calculate the confidence interval of each parameter to be determined based on the n groups of estimated values ​​of the parameter to be determined, determine the estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of each parameter to be determined, and determine the target value corresponding to the parameter to be determined based on the estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of the parameter to be determined.

[0169] We have previously estimated six parameters using multiple sets of test data and the optimization of a nonlinear system of equations. Given a substantial sample size, we can reasonably assume that the approximate values ​​of the parameters obtained will contain some error. Statistical analysis of the calculation results allows us to estimate the values ​​of the desired parameters, and interval estimation allows us to determine the reasonable range of values ​​for the desired parameters.

[0170] It can be understood that for each parameter to be determined, n estimated values ​​are obtained by solving the nonlinear constraint equation, and then a reasonable estimated value is selected from these n estimated values ​​using statistical methods.

[0171] Assume that the inversion matrix of the six parameters to be determined is obtained by solving the equation group as X=(X1, X2, ..., X6), where X1, X2, ..., X6 represent n-dimensional vectors of the inversion calculation results for each parameter to be determined.

[0172] Assume that the estimated value of the parameter to be determined is μ i , now we need to i Confidence interval estimation is performed. When the sample size of the test data (ie n) is sufficient, the mean of the inversion results of each parameter is calculated. and sample variance S i :

[0173]

[0174] but Obey the t distribution, that is

[0175] Based on the above analysis, it is obvious that

[0176]

[0177] Right now

[0178]

[0179] μ i The confidence interval with a confidence level of 1-α is

[0180]

[0181] where t α / 2 (n-1) can be obtained by looking up the table, and generally α=0.05 can be taken, that is, the confidence level is 95%.

[0182] In summary, the confidence interval for each parameter to be determined can include:

[0183]

[0184] Where, is the average of the n estimated values ​​of the i-th parameter to be determined, S i is the variance of the n estimated values ​​of the i-th parameter to be determined, the confidence level is 1-a, a is the preset value, t α / 2 (n-1) can be obtained by looking up the table.

[0185] It is understandable that if only one of the n estimated values ​​for a parameter falls within the corresponding confidence interval, then this estimate that falls within the confidence interval can be used as the final parameter value, i.e., the target value. If multiple estimates fall within the confidence interval, these estimates that fall within the confidence interval can be further processed (for example, averaged), and the final parameter value obtained is the target value.

[0186] As can be seen, the method provided by the present invention first establishes a relationship equation between the effective infrared radiation data of each bin, multiple environmental parameters, and multiple parameters to be determined. Then, n*m sets of test data are obtained and input into the relationship equation to obtain n estimated values ​​for each parameter to be determined. A corresponding confidence interval is then calculated for each parameter to be determined, and reasonable estimated values ​​are screened based on the confidence intervals. Finally, the target value of the parameter to be determined is determined based on the screened estimated values. The relationship equation in the present invention can reflect the relationship model of the mutual coupling between the ship target and the environment. Then, real test data (including apparent infrared radiation data from the thermal imager and environmental parameters) is collected and input into the relationship equation, resulting in a constraint equation with the parameters to be determined as variables. After solving the constraint equation, the calculated estimated values ​​are screened by calculating confidence intervals, and the final target value is determined based on the screened estimated values. As can be seen, starting from infrared radiation theory, the present invention establishes a relationship equation for the coupling between the target and the environmental background, and obtains a target value at a certain confidence level, effectively solving the problem of inaccurate infrared characteristic modeling and simulation calculations for non-cooperative targets. That is, the present invention studies the mechanism of the infrared radiation characteristics of ship targets, forms a parameterized theoretical model of the mutual coupling between ship targets and the sea and sky environment, and combines measured data to carry out inversion technology research on the parameters to be determined of non-cooperative targets, so as to solve the problem of "untrue simulation" of the infrared characteristics of ship targets under complex marine environment conditions, that is, to improve the accuracy of the parameters to be determined, thereby further improving the simulation degree of the infrared characteristics of ship targets.

[0187] In a second aspect, the present invention provides a device for determining parameters affecting infrared characteristics of a ship, the device comprising:

[0188] The equation pre-building module is used to pre-establish the relationship equations between the effective infrared radiation data of each facet on the ship target, multiple environmental parameters and multiple parameters to be determined;

[0189] a data acquisition module, configured to acquire n*m ​​groups of test data corresponding to the bin of the ship target in an actual scene; wherein each group of test data includes the apparent infrared radiation data of the corresponding pixel point of the ship target in the thermal imager and a plurality of corresponding environmental parameters, where m is the number of parameters to be determined, and n is a positive integer greater than 1;

[0190] an equation solving module, configured to input each m groups of test data into the relational equation to obtain a group of nonlinear constraint equations with the multiple parameters to be determined as variables, and solve each group of nonlinear constraint equations using Newton's method to obtain a corresponding group of estimated values ​​of the parameters to be determined; wherein each group of estimated values ​​of the parameters to be determined includes an estimated value of each parameter to be determined, and n*m groups of test data correspond to n groups of estimated values ​​of the parameters to be determined;

[0191] The interval screening module is used to calculate the confidence interval of each parameter to be determined based on the n groups of estimated values ​​of the parameter to be determined, determine the estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of the parameter to be determined, and determine the target value corresponding to the parameter to be determined based on the estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of the parameter to be determined.

[0192] In some embodiments, the relational equation constructed by the equation pre-building module includes:

[0193]

[0194] Where ε is the radiation emissivity of the surface element at room temperature, ir is the infrared band emissivity of the hull surface, L app，i is the effective infrared radiation data of the i-th pixel on the thermal imager, L sea is the sea surface radiance, F i，sea is the radiation angle coefficient from the ith surface element to the sea surface, L sky is the sky background radiance, F i，sky is the radiation angle coefficient from the i-th surface element to the sky hemisphere, E sun is direct solar radiation, θ i is the angle between the normal vector of the ith element and the direction of the sun, h out is the external flow field convection heat transfer coefficient, h in is the cabin convection heat transfer coefficient, T i is the thermodynamic temperature of the i-th element, α is the radiation absorption rate in the visible light band, is the direct solar radiation intensity, is the solar scattered radiation illuminance, ε is the radiation emissivity in the normal temperature band, T in is the cabin air temperature, T air is the atmospheric temperature, E sky is the sky hemispheric radiance, E sea is the radiation emittance of the sea surface; the i-th pixel point of the thermal imager corresponds to the i-th surface element on the ship target, ε ir ,ε,α,h out 、h in and T in is the parameter to be determined, L sea 、F i，sea , L sky 、F i，sky 、E sun ,θ i 、 T air 、E sky and E sea For environmental parameters.

[0195] In some embodiments, the confidence interval corresponding to each parameter to be determined includes:

[0196]

[0197] Where, is the average of the n estimated values ​​of the i-th parameter to be determined, S i is the variance of the n estimated values ​​of the i-th parameter to be determined, the confidence level is 1-a, a is the preset value, t α / 2 (n-1) can be obtained by looking up the table.

[0198] It is understandable that the device provided in this aspect corresponds to the method provided in the first aspect. For examples, implementation methods, beneficial effects, etc. of the relevant content, please refer to the corresponding parts in the first aspect and will not be repeated here.

[0199] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0200] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0201] Through the above description of the embodiments, those skilled in the art will clearly understand that the above-mentioned embodiments and methods can be implemented using software plus the necessary general-purpose hardware platform. Of course, hardware can also be used, but in many cases the former is a more preferred embodiment. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as RON / RAN, magnetic disk, or optical disk) and includes a number of instructions for enabling a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in various embodiments of the present invention.

[0202] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for determining parameters affecting infrared characteristics of a ship, characterized in that: include: Establish in advance the relationship equations among the effective infrared radiation data of each facet on the ship target, multiple environmental parameters and multiple parameters to be determined; Obtaining n*m sets of test data corresponding to the bin of the ship target in an actual scene; wherein each set of test data includes apparent infrared radiation data of the corresponding pixel point of the ship target in the thermal imager and corresponding multiple environmental parameters, m is the number of the parameters to be determined, and n is a positive integer greater than 1; Inputting each m groups of test data into the relational equation to obtain a group of nonlinear constraint equations with the multiple parameters to be determined as variables, and solving each group of nonlinear constraint equations using Newton's method to obtain a corresponding group of estimated values ​​of the parameters to be determined; wherein each group of estimated values ​​of the parameters to be determined includes an estimated value of each parameter to be determined, and n*m groups of test data correspond to n groups of estimated values ​​of the parameters to be determined; Calculating a confidence interval for each parameter to be determined based on the n groups of estimated values ​​of the parameter to be determined, determining an estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of the parameter to be determined, and determining a target value corresponding to the parameter to be determined based on the estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of the parameter to be determined; The confidence interval corresponding to each parameter to be determined includes: Where, is the average of the n estimated values ​​of the i-th parameter to be determined, S i is the variance of the n estimated values ​​of the i-th parameter to be determined, the confidence level is 1-a, a is the preset value, t α / 2 (n-1) can be obtained by looking up the table.

2. The method according to claim 1, characterized in that The relationship equation includes: Where ε is the radiation emissivity of the surface element at room temperature, ε ir is the infrared band emissivity of the hull surface, L app，i is the effective infrared radiation data of the i-th pixel on the thermal imager, L sea is the sea surface radiance, F i，sea is the radiation angle coefficient from the ith surface element to the sea surface, L sky is the sky background radiance, F i，sky is the radiation angle coefficient from the i-th surface element to the sky hemisphere, E sun is direct solar radiation, θ i is the angle between the normal vector of the ith element and the direction of the sun, h out is the external flow field convection heat transfer coefficient, H in is the cabin convection heat transfer coefficient, T i is the thermodynamic temperature of the i-th surface element, α is the radiation absorption rate in the visible light band, E sundir is the direct solar radiation intensity, E sundif is the solar diffuse irradiance, T in is the cabin air temperature, T air is the atmospheric temperature, E sky is the sky hemispheric radiance, E sea is the radiation emittance of the sea surface; the i-th pixel point of the thermal imager corresponds to the i-th surface element on the ship target, ε ir ,ε,α,h out 、H in and T in is the parameter to be determined, L sea 、F i，sea , L sky 、F i，sky 、E sun ,θ i 、 E sundir 、 E sundif 、T air 、E sky and E sea For environmental parameters.

3. The method according to claim 2, characterized in that The temperature of any point inside the hull steel plate that is not on the boundary is calculated using the first formula, which includes: Where λ is the thermal conductivity of the hull steel plate, ρ is the density of the hull steel plate, and c is the specific heat capacity of the hull steel plate.

4. The method according to claim 2, characterized in that The temperature of any point on the inner wall of the hull is calculated using the second formula, which includes: Where λ is the thermal conductivity of the hull steel plate, iso is the thermal conductivity of the insulation layer, D iso is the thickness of the insulation layer.

5. The method according to claim 2, characterized in that The temperature of any point on the outer wall of the ship is calculated using the third formula, which includes: Where λ is the thermal conductivity of the hull steel plate, D is the thickness of the hull steel plate, Q rd is the radiation heat transfer coefficient between the hull surface and the environment.

6. The method according to claim 1, characterized in that The Newton method is used to solve each set of nonlinear constraint equations to obtain a corresponding set of estimated values ​​of the parameters to be determined, including: S1. Set the initial iteration vector formed by m parameters to be determined , let k = 0; S2, let the nonlinear constraint equations be F(x), calculate F(x (0) ); S3, let A0=J(x (0) ), J(x (0) ) is F(x (0) ), calculate the Jacobian matrix of ; S4. Calculation ; S5. Calculate F(x (k+1) ); S6. Let y k+1 = F(x (k+1) ) - F(x (k) ), s k+1 = x (k+1) - x (k) ; S7, command ; S8, command ; S9, judge ||x (k+2) -x (k+1) ||<e is true, e is a preset value close to 0; if so, exit the iteration process and set x (k+2) As the solution of the nonlinear constraint equations; otherwise, k=k+1, return to S5.

7. A device for determining parameters affecting infrared characteristics of a ship, characterized in that: include: The equation pre-building module is used to pre-establish the relationship equations between the effective infrared radiation data of each facet on the ship target, multiple environmental parameters and multiple parameters to be determined; a data acquisition module, configured to acquire n*m ​​groups of test data corresponding to the bin of the ship target in an actual scene; wherein each group of test data includes the apparent infrared radiation data of the corresponding pixel point of the ship target in the thermal imager and a plurality of corresponding environmental parameters, where m is the number of parameters to be determined, and n is a positive integer greater than 1; an equation solving module, configured to input each m groups of test data into the relational equation to obtain a group of nonlinear constraint equations with the multiple parameters to be determined as variables, and solve each group of nonlinear constraint equations using Newton's method to obtain a corresponding group of estimated values ​​of the parameters to be determined; wherein each group of estimated values ​​of the parameters to be determined includes an estimated value of each parameter to be determined, and n*m groups of test data correspond to n groups of estimated values ​​of the parameters to be determined; an interval screening module, configured to calculate a confidence interval for each parameter to be determined based on the n groups of estimated values ​​of the parameter to be determined, determine an estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of the parameter to be determined, and determine a target value corresponding to the parameter to be determined based on the estimated value of each parameter to be determined that falls within the corresponding confidence interval among the n estimated values ​​of the parameter to be determined; The confidence interval corresponding to each parameter to be determined includes: Where, is the average of the n estimated values ​​of the i-th parameter to be determined, S i is the variance of the n estimated values ​​of the i-th parameter to be determined, the confidence level is 1-a, a is the preset value, t α / 2 (n-1) can be obtained by looking up the table.

8. The device according to claim 7, characterized in that The relational equation constructed by the equation pre-building module includes: Where ε is the radiation emissivity of the surface element at room temperature, ε ir is the infrared band emissivity of the hull surface, L app，i is the effective infrared radiation data of the i-th pixel on the thermal imager, L sea is the sea surface radiance, F i，sea is the radiation angle coefficient from the ith surface element to the sea surface, L sky is the sky background radiance, F i，sky is the radiation angle coefficient from the i-th surface element to the sky hemisphere, E sun is direct solar radiation, θ i is the angle between the normal vector of the ith element and the direction of the sun, h out is the external flow field convection heat transfer coefficient, H in is the cabin convection heat transfer coefficient, T i is the thermodynamic temperature of the i-th surface element, α is the radiation absorption rate in the visible light band, E sundir is the direct solar radiation intensity, E sundif is the solar diffuse irradiance, T in is the cabin air temperature, T air is the atmospheric temperature, E sky is the sky hemispheric radiance, E sea is the radiation emittance of the sea surface; the i-th pixel point of the thermal imager corresponds to the i-th surface element on the ship target, ε ir ,ε,α,h out 、H in and T in is the parameter to be determined, L sea 、F i，sea , L sky 、F i，sky 、E sun ,θ i 、 E sundir 、 E sundif 、T air 、E sky and E sea For environmental parameters.

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