70 results about "Acoustic testing" patented technology

The present application belongs to the field of rock burst risk assessment of deep rock engineering, and particularly relates to a quantitative evaluation method for rock burst tendency of surrounding rock under multiple disturbances, which comprises the following steps: obtaining the distribution depth of excavation damage zone through acoustic testing, and obtaining the average wave velocity of rock mass in the range of original rock zone; obtaining the geological strength index and disturbance factor through the average wave velocity; further obtaining the residual elastic energy of surrounding rock based on the geological strength index and disturbance factor, and evaluating the rock burst tendency of surrounding rock through the residual elastic energy of surrounding rock; the acoustic testing points of surrounding rock are unchanged, and the rock burst tendency of surrounding rock is evaluated after each excavation footage of the working face is completed, until the distribution characteristics of rock burst tendency no longer change obviously, which is taken as the long-term evaluation result of rock burst tendency of surrounding rock. The quantitative evaluation formula of rock burst tendency of surrounding rock considers the rock mass structure effect, which is reflected in the geological strength index, and considers the excavation disturbance effect, which is consistent with the actual situation of engineering construction process, and has strong practicability.

The present application belongs to the technical field of oil and gas drilling, and particularly relates to a multiphase fluid acoustic and electric testing device and method for drilling overflow simulation. The device is characterized in that: a multifunctional interface integrated on the upper part of the pressure-resistant reaction kettle cylinder is used to complete the injection of different component multiphase fluids and pressure setting; a heating jacket is used to complete the setting of a predetermined temperature; and continuous stirring is used to make the multiphase fluid reach a stable state with uniform composition. Under the conditions of a set temperature and pressure, electrical and acoustic signals are collected to analyze the multiphase fluid. The electrical testing component distinguishes different fluid components by monitoring the changes of resistance and dielectric constant; and the acoustic monitoring component detects the content of bubbles in the fluid through acoustic signals. The acoustic and electric cooperative monitoring can effectively distinguish different overflow types such as gas invasion, oil invasion and water invasion, and overcome the limitations of single monitoring method, thereby providing a reliable technical means for the mechanism research and practical application of downhole overflow monitoring.

This utility model discloses a support and acoustic testing system used inside an anechoic chamber. The support includes a telescopic rod, a linkage mechanism, and a tray. The telescopic rod has a fixed rod and a movable rod that are slidably engaged. One end of the fixed rod is provided with a fixing part for fixed connection with the side wall of the anechoic chamber. The linkage mechanism includes a guide rod fixedly connected to the movable rod, a swing rod hinged to the guide rod, and a push rod diagonally supported between the guide rod and the swing rod. One end of the push rod is hinged to the swing rod, and the other end is hinged to a slider slidably disposed on the guide rod. The slider is provided with a locking element for locking the slider. The tray is used to place the test object for acoustic testing, and the bottom of the tray is connected to the swing rod. The support of this utility model can easily adjust the position of the test object inside the anechoic chamber, thereby improving the efficiency of acoustic testing.

The invention relates to the technical field of surrounding rock blasting vibration reduction, and discloses a vibration reduction method and system for surrounding rock blasting under complex geological conditions, which are used for solving the problems of surrounding rock instability, structure damage and the like caused by blasting vibration in complex geological environments. The method comprises the following steps: 1) geological investigation and risk grading: acquiring parameters by using geological radar, drilling sound wave test and the like, and dividing risk areas; (2) blasting parameters are optimized, and the explosive loading amount, delay time and the like are adjusted according to different risk areas; (3) a vibration reduction scheme is formulated, and measures such as damping grooves, rubber pads and grouting reinforcement are adopted; and 4) monitoring feedback, collecting vibration data in real time and correcting the scheme. The system is composed of a control center, a geological survey module, a parameter design module, a vibration reduction arrangement module and a monitoring feedback module, and vibration reduction control is achieved. Through geological accurate pre-judgment, parameter dynamic optimization and multi-dimensional vibration reduction, the blasting vibration influence is reduced, the safety of surrounding rock and surrounding structures is guaranteed, and the method is suitable for engineering scenes such as tunnel excavation and mining.

A modular adjustable fixing device for an underwater acoustic transducer array includes a main support rod, a central structural component, a transducer fixing ring, and a sliding connector. One end of the main support rod is fixedly connected to the interior of the central structural component through three sets of square holes. The other end extends to form a Y-shaped array frame. The extended end of the main support rod is used to fix the transducer fixing ring, which is fixed to the main support rod by the sliding connector and suspended from the rear side of the central structural component. The sliding connector is slidably fitted onto the main support rod and positioned by fasteners, with its end connected to the transducer fixing ring. The central transducer fixing ring is fixed to the top of the central structural component. This invention allows for flexible adjustment of the baseline length of the underwater acoustic transducer array by adjusting the position of the sliding connector, meeting the acoustic testing requirements of different array models. Furthermore, its modular design facilitates easy disassembly and is suitable for stable fixing of transducer arrays in complex aquatic environments.

One or more aspects of the present disclosure are directed to fixturing mechanisms for placement of battery cells inside an ultrasonic testing system. The disclosed fixturing mechanisms enable accurate and predictable loading, placement, and unloading of battery cells inside ultrasonic testing systems allowing all faces of battery cells of different types (e.g., pouch cells, prismatic cells, cylindrical cells, etc.) to have sufficient exposure to transmission and reception of acoustic signals. This fixturing mechanism furthers the goal of providing a robustly designed ultrasonic test system and producing accurate inspection results for batteries.

The invention provides a sound wave testing device and testing method suitable for an ultra-low-speed rock-soil mass, and relates to the technical field of in-hole rock mass sound wave testing, the device comprises a testing probe and a medium storage device, the testing probe comprises a plurality of vibration pickups and an elastic straight tube capsule, the vibration pickups are sequentially connected through high-strength thin wires, and the elastic straight tube capsule sleeves the vibration pickups; one end of the elastic straight-barrel capsule is connected with a second plugging piece which is internally provided with a liquid flow meter, the second plugging piece is communicated with one end of the medium storage device through a hydraulic quick connector, and the other end of the elastic straight-barrel capsule is connected with a first plugging piece which is internally provided with a micro water pump; rubber protection rings are arranged at the joints of the elastic straight-barrel capsule and the first plugging piece and the second plugging piece; a water inlet pipe and a water outlet of the micro water pump are arranged in the elastic straight-barrel capsule; a first hollow pipe is arranged at the other end of the medium storage device and is used for injecting a supersaturated low-speed solution or gas into the test probe and the medium storage device. The low-speed longitudinal wave of the rock mass can be obtained more accurately.

The invention discloses a sleep aiding cabin sound insulation test system and method based on multi-source data analysis, and relates to the technical field of sleep aiding cabin acoustic tests.According to the sleep aiding cabin sound insulation test system and method, characteristic environment parameters and characteristic coordinate points corresponding to sound pressure parameters are obtained, and sound pressure parameters of the characteristic environment parameters and the characteristic coordinate points are obtained according to the sound pressure parameters of the characteristic environment parameters and the characteristic coordinate points; calculating to obtain sound ring parameters of the characteristic coordinate points, calculating to obtain sound vibration parameters of the characteristic coordinate points according to sound vibration transmission ratios and vibration energy of the characteristic coordinate points, calculating to obtain sound engineering parameters according to the working condition scores and sound pressure parameters of the characteristic coordinate points, and calculating to obtain health scores; calculating to obtain a health score threshold range, training by constructing an abnormal data set, and generating an abnormal duration prediction formula; and according to the real-time data of the current work, whether a worker needs to carry out maintenance is judged, and the duration of next maintenance is calculated, so that efficient maintenance management is realized, and a guarantee is provided for equipment operation.

The invention provides an active compensation sound transmission method and device based on an actual installation environment of a sound transmission screen, and the method comprises the steps: obtaining a to-be-played audio corresponding to a target sound transmission screen in the actual installation environment; selecting a corresponding target audio compensation value from a target compensation parameter table; performing pre-compensation processing on the to-be-played audio to obtain a pre-compensated audio; playing the pre-compensated audio through a loudspeaker; wherein the actual audio obtained after the pre-compensation audio passes through the target sound transmission screen has the same audio characteristic as the audio to be played. According to the mode, the target audio compensation value corresponding to the to-be-played audio is selected from the target compensation parameter table and is compensated, and the target compensation parameter table integrates the reference attenuation table measured in the standard acoustic test environment and the environment compensation increment table measured in the actual installation environment, so that the accuracy of the target audio compensation value is improved. The influence of the actual installation environment is comprehensively considered, and the pre-compensation audio is played through the target sound transmission screen, so that the auditory effect of the audience side after the sound penetrates through the screen can be improved.

The utility model relates to the field of buildings, in particular to a non-destructive testing device for the pile forming quality of a secant pile, which comprises four steel pipes embedded around the secant pile and a supporting seat, a placing platform is erected at the top of the supporting seat, and corresponding first motors are arranged at the positions, opposite to the steel pipes, of the placing platform. According to the utility model, the supporting seat is erected above the steel pipe, and then the controller connected with the first motor is used for controlling the first motor to drive the take-up roller to rotate so as to slowly lay down the detection line, so that the ultrasonic detection probe is lowered to enter the steel pipe for sound wave detection; in the detection process, whether the secant pile is broken or not is checked by feeding back the detection line to the detector, the secant pile needs to be knocked to achieve sound wave detection in the detection process, in this way, it is not needed to conduct core drilling to check the internal situation of the secant pile, and nondestructive testing is achieved.

The application relates to the technical field of phase change material research, and discloses an acoustic characterization equipment for detecting structural characteristics of phase change materials, which comprises a sample, a test reaction kettle, an acoustic test assembly, a temperature control assembly, a pressure control assembly and a data acquisition assembly; wherein the sample is in a cylindrical structure, the outer side of which is wrapped with three layers of latex film and one layer of tin paper; the test reaction kettle comprises a reaction kettle shell and a reaction kettle base; the acoustic test assembly is provided with two groups, which are installed at the upper and lower ends of the sample and used for emitting acoustic waves with different frequencies so as to obtain the attenuation characteristics and internal structural characteristics of the test material. The application realizes the preparation and acoustic test of phase change materials with different structures under different temperature and pressure conditions. Compared with other equipment, the equipment can not only realize the acoustic test of the phase change process of the phase change material under high net confining pressure, but also can carry out acoustic tests with frequency changes and different waveforms without replacing the acoustic probe.

This utility model discloses an acoustic testing system for a directional sound-emitting device, including an audio analyzer, an audio processing unit, a power amplifier, a transformer unit, a DC power supply, and a pickup unit. The audio analyzer provides audio, which is then processed as a digital audio signal by the audio processing unit. The processed audio is amplified by the power amplifier, and after exiting the power amplifier, it is amplified again by the transformer. With the DC bias provided by the DC power supply, it is then connected to the directional sound-emitting device under test. The sound emitted by the directional sound-emitting device is received by the pickup unit and returned to the audio analyzer, which displays the frequency response and distortion curves. This utility model provides a novel acoustic testing platform that enables rapid testing of the acoustic performance of directional sound-emitting devices.

Provided is a hand emulator and an acoustic testing system. The hand emulator includes: a main support configured to support a device under test, the main support includes a palm, a thumb, an index finger, a middle finger, a ring finger and a little finger that are movably arranged at an end of the palm; a stopper including a plurality of limit pillars, at least some of the plurality of limit pillars are arranged on the palm, several limit pillars of the plurality of limit pillars enclose to form an accommodating space, and the device under test is limited within the accommodating space. The hand emulator can measure the frequency response of the speaker and / or the microphone of the device under test, emulate acoustic characteristics similar to the user's hand, and accurately and repetitively position the device under test, which improves existing measurement standards and creates new testing methods.

The invention discloses a drilling sound wave testing device and method suitable for fractured rock mass, and the device comprises an outer cylinder which is provided with a mounting cavity in the center; the sound wave emission probe is mounted in the mounting cavity; the sound wave receiving probe is mounted in the mounting cavity; the number of the inflatable sealing discs is two, the two inflatable sealing discs are both installed on the periphery of the outer cylinder and located at the upper end and the lower end of the outer cylinder correspondingly, and the inflatable sealing discs can be inflated so that the periphery can be expanded to make sealing contact with the hole wall; and the inflating and exhausting mechanism is partially arranged in the mounting cavity in a penetrating manner and is used for inflating or exhausting the inflating sealing disc. According to the device disclosed by the invention, the two inflatable sealing discs which are respectively mounted at the upper end and the lower end of the outer cylinder are adopted, after the inflatable sealing discs are inflated through the inflation and exhaust mechanism, the peripheries of the inflatable sealing discs can be uniformly expanded and are tightly attached to irregular hole walls of the fractured rock mass, and a closed test space is formed between the two inflatable sealing discs. Interference of sound wave signals in the propagation process is reduced, and the quality of signal acquisition and the reliability of test results are improved.

The application relates to the technical field of acoustic wave testing, in particular to an acoustic wave testing equipment for underground caverns; the equipment comprises a tester and a transducer connected with the tester through a wire; the transducer transmits waves and transmits signals to the tester through the wire after receiving the waves; the transducer is fixedly connected with an elastic pipe through a transducing seat; an elastic liquid inlet pipe and an elastic gas outlet pipe pass through the elastic pipe; one end of the liquid inlet pipe is connected with the outer wall of the transducing seat, and the other end is connected with a water pump; in the process of approaching the testing hole, the two pushing chains are turned inward and combined to form a pushing piece; in the process of moving away from the testing hole, the two pushing chains are turned outward and separated; thus, the testing equipment can meet the testing requirements of testing holes with different depths, the pushing piece can be combined and separated quickly, the testing efficiency is high, and the equipment can be used in the space-limited surroundings of some testing hole orifices.

1. Name of the designed product: anechoic chamber. 2. Use of the designed product: the designed product is used in a laboratory for acoustic testing. 3. Design points of the designed product: in shape. 4. Picture or photo best indicating the design points: B-B sectional view.

The invention relates to the technical field of acoustic detection and signal processing equipment, in particular to a portable AI sound spectrum analyzer device and a use method thereof. The device comprises a box body, an embedded control panel, a tool assembly, a power supply module and an acquisition connection module. The tool assembly comprises a quick-change profiling support and a miniature vibration sensor, and a sound collector support supports three-dimensional adjustment. The embedded control panel is integrated with an AI sound spectrum analysis system, and end side noise reduction can be carried out on high-fidelity audio and vibration signals. The beneficial effects of the invention are that: through the integration of the modular tool, the multi-degree-of-freedom sound collection structure, the high-fidelity collection link and the embedded AI reasoning engine, the problems that equipment cannot be moved, the tool cannot be reused, the noise suppression capability is weak and the analysis intelligence degree is low in the acoustic detection of multi-class products in the industrial field are solved.

The utility model provides a general type headset audio frequency test fixture, include: support base, support subassembly, the number is two, opposite be located on support base, acoustic simulation subassembly, the number is two, set up respectively on two support subassembly, push subassembly, the number is two, be used for pushing two measured object to be close in acoustic simulation subassembly respectively, simulation mouth, between two acoustic simulation subassembly, wherein, support subassembly includes support piece and sets up the suction subassembly on support piece, the suction subassembly is used for sucking acoustic simulation subassembly, the utility model provides a general type headset audio frequency test fixture can promote the general property of headset's acoustic test to and promote test effect and test accuracy.

This invention provides an acoustic testing method and system. The acoustic testing method includes: acquiring one or more test data points for each of a plurality of products under test, each test data point including multiple frequency values ​​and a corresponding test value for each frequency value; determining whether the test value corresponding to each frequency value in each test data point meets the corresponding specifications; if the test value corresponding to each frequency value in a test data point meets the corresponding specifications, then the test data point is considered valid; otherwise, the test data point is considered invalid; classifying the multiple invalid test data points to obtain test data of multiple failure types, and calculating the proportion of test data of each failure type; inferring the cause of failure of the product under test based on the test data of each failure type and its proportion. This allows for in-depth analysis of invalid test data and tracing the root cause of failure.

The utility model discloses a motor controller NVH acoustic test tool, which comprises a sample piece supporting table, a damper spring and a supporting base, the damper spring is located between the sample piece supporting table and the supporting base, the sample piece supporting table comprises a body and a plurality of fixing ends arranged on the body and used for fixing a motor controller, and the fixing ends are used for fixing the motor controller. The fixing end is provided with a bolt hole, and a first reinforcing rib is arranged around the bolt hole according to the height and the structural strength of the motor controller supporting foot. According to the motor controller NVH acoustic test tool disclosed by the utility model, a tool jig capable of simulating real installation rigidity is designed, the tool jig structurally comprises the sample piece supporting table, the damper spring and the supporting base, the real installation state of the motor controller is simulated, the test accuracy is improved, and accurate evaluation of structural acoustic performance of the motor controller is facilitated.

The utility model discloses a closed test silence room with a double-layer wall structure, which comprises a silence room outer shell, an expansion box communicated with the interior of the silence room outer shell is fixedly mounted on the front surface of the silence room outer shell, an external loose-leaf door is hinged to the front surface of the expansion box, and a storage groove is formed in the side wall of the expansion box. The double-layer wall structure of the metal outer wall and the glass fiber inner wall is adopted, the sound insulation cotton is filled between the metal outer wall and the glass fiber inner wall, external noise, especially low-frequency noise, is effectively blocked, the purity of the acoustic environment in the silence room is ensured, the shock pad can reduce interference of vibration of internal equipment on acoustic testing, and the testing accuracy is further improved. And meanwhile, leakproofness and convenience for people to go in and out are achieved through the design of the expansion box and the double doors, external noise can be prevented from permeating even in the testing process, air circulation in the mute room is achieved through the air exchange assembly arranged at the top, and it is ensured that interference cannot be introduced in the air exchange process.

The application relates to the technical field of micro receiver manufacturing, and discloses a digital production closed-loop control system for micro receiver manufacturing, which comprises an industrial computer, a bottom field bus, a plurality of dispensing work stations, pressing work stations, UV curing work stations and acoustic testing work stations which are sequentially arranged along the production flow direction, and a tracking module, an addressing module, a pre-judging module, a routing module and an iteration module which are arranged in the industrial computer. The primary pressing compensation depth is calculated by obtaining the actual dispensing quality, the boundary is cut off in combination with the safe pressing limit interval to prevent mechanical damage of internal components, displacement residual deviation generated by the boundary cutting is converted into an energy compensation instruction of a downstream UV curing work station to absorb size errors that cannot be eliminated in the mechanical domain, a joint prediction residual is constructed by using a line tail measured resonance frequency, a local control model is directionally iteratively corrected in combination with physical symbol constraints, and the stability of the closed-loop control in long-term continuous production is ensured.

The application discloses a kind of underground cavern edge crown acoustic testing devices, it is related to physical detection technical field;And the present application includes testing mechanism and test borehole, testing mechanism is used in cooperation with test borehole, and one end of testing mechanism is equipped with the first sealing mechanism used in cooperation with test borehole;Under the coordination of first sealing mechanism and second sealing mechanism, the sealing property of the connecting place between test casing and test borehole and between test casing and test push rod can be effectively improved, so that the accuracy of test data can be effectively improved, under the coordination of rotating mechanism and marking mechanism, the paint can be sprayed to the outer wall of the hole of abnormal test borehole by the cooperation of guide paint pipeline and paint spraying pipeline, so that rapid marking is realized, and the subsequent user can conveniently carry out corresponding processing on the test borehole, and the user does not need to manually mark, thereby saving manpower.

The invention relates to an acoustic test system 10 for at least one motor vehicle component 14. The acoustic test system 10 comprises a surface 16 configured to support the at least one motor vehicle

The utility model discloses a kind of handset test tool, including fixed plate, artificial ear and arc dust cover, the fixed plate is equipped with the placement groove and test mouth of intercommunication;The artificial ear touches the fixed plate, and the pickup port of the artificial ear is connected with the test mouth;The arc dust cover is connected with the fixed plate, and the arc dust cover is at least partially located in the pickup port.The handset test tool has arc dust cover, can effectively prevent external dust from invading artificial ear, prevent dust from gathering in artificial ear, benefit to prolong the service life of artificial ear.Compared with plane dust cloth, arc dust cover has larger sound-transmitting area, which is beneficial to reduce the influence on acoustic test, and furthermore, arc dust cover has lower resonance risk, which is beneficial to ensure the accuracy of test results.

The utility model discloses an extensible closed test silence room, which comprises two silence room main body frames, uniformly distributed connecting grooves are arranged on the silence room main body frames, uniformly distributed connecting columns are arranged between the two silence room main body frames, and two ends of each connecting column are respectively positioned in the two connecting grooves. According to the silence room, the silence room body frame is matched with the connecting columns and the connecting rods, stable assembly is achieved, the structural stability and durability are ensured, the first sound insulation plate and the second sound insulation plate are slidably installed to form a seamless sound insulation space, external noise is effectively isolated, and a precise environment is provided for acoustic testing; by disassembling the sound insulation plate II and adding a new mute room main body frame, flexible expansion is realized, test requirements of different scales are met, reconstruction cost is avoided, disassembly and assembly are convenient due to modular design, diversified scene requirements are met, and the mute room is suitable for industries such as electronics, machinery, automobiles, aerospace and the like.

This invention provides an acoustic testing system that integrates an underwater mobile and a fixed measurement array. The system includes an underwater vehicle platform, a fixed underwater measurement array, a spatiotemporal calibration module, and a sound source control and modulation module. The underwater vehicle platform carries a sound source transmitting device, attitude sensor, position beacon, and communication module. The fixed underwater measurement array receives acoustic signals from underlying targets and reference acoustic signals transmitted by the vehicle platform. The spatiotemporal calibration module ensures consistency between the test signals acquired by the vehicle platform and the measurement array. The sound source control and modulation module generates different acoustic test signals according to mission requirements. By integrating the underwater vehicle platform and the fixed underwater measurement array, this invention constructs a reconfigurable, high-precision, and spatiotemporally consistent acoustic testing system, achieving underwater acoustic testing capabilities with greater coverage, higher measurement accuracy, and stronger data consistency under complex sea conditions.

The invention discloses a magnesia carbon brick online quality inspection method and system based on knocking detection, and relates to the field of acoustic detection, a reciprocating swing knocking mechanism driven by a stepping motor is adopted to carry out fixed-point knocking on the surface of a magnesia carbon brick according to a preset interval, and multichannel knocking sound wave signals are synchronously collected through a pickup array; time domain, frequency domain and time-frequency domain features are extracted from the preprocessed sound wave signals, and a fusion feature vector is constructed after normalization processing; and inputting the fusion feature vector into an attention mechanism enhanced extreme learning machine model, and outputting the defect type and confidence of the magnesia carbon brick. According to the invention, visual identification and self-adaptive regulation and control technologies are combined, real-time detection can be completed without stripping a production process, the detection rate is greatly improved, and continuous operation requirements of an automatic production line are met. Characteristic parameters of magnesia carbon brick materials are deeply fused into the whole process of detection parameter regulation and control, signal processing and model construction, and accurate recognition and grading of different types of defects are achieved by means of an intelligent model with an attention mechanism enhanced.

The utility model relates to the technical field of silencing sheets, and discloses a tool for testing the sound absorption performance of a silencing sheet, which comprises a silencer and a fan device arranged on one side of the silencer, one side of the fan device is communicated with a connecting pipe, one end of the connecting pipe is communicated with a sound source protection box, an artificial sound source is arranged in the sound source protection box, and the artificial sound source is connected with the fan device. One side, far away from the connecting pipe, of the sound source protection box is communicated with a ventilation pipeline, one end of the ventilation pipeline is communicated with a test channel, and two symmetrical silencing sheet bodies are arranged at the corner of the test channel. Boundary conditions and dynamic working conditions of actual working conditions are simulated, experimental testing of the silencing piece under the actual working conditions is achieved, and the real silencing amount testing result of the silencing piece is guaranteed; acoustic testing of the silencing sheet under various working conditions such as dynamic working conditions, non-dynamic working conditions and dynamic working conditions with different parameters can be realized.

This utility model relates to an alternating feeding fixture and an acoustic testing chamber, comprising a base, a guide plate, a rodless cylinder, a synchronous belt assembly, a first material rack, and a second material rack. The guide plate is connected to the base and has a guide groove. The rodless cylinder and the synchronous belt assembly are respectively connected to the base. The first material rack includes a first loading plate slidably connected to the base and connected to the synchronous belt. The second material rack includes a sliding seat and a second loading plate. The sliding seat is slidably connected to the base and respectively connected to the rodless cylinder and the synchronous belt. Multiple sliding rods are slidably arranged on the sliding seat, each sliding rod being connected to the second loading plate. A connecting arm is connected to the second loading plate, and a guide member rotatably connected to the guide groove is rotatably arranged on the connecting arm. This alternating feeding fixture can realize the avoidance action during the synchronous movement of the two material racks, and can realize the synchronous loading and unloading, thereby effectively shortening the testing cycle and improving the efficiency of product testing.