A method for assessing liquid cargo consumption during unsteady ship navigation

Abstract

This invention provides a method for assessing liquid cargo consumption during unsteady voyages. The method involves inputting the collected data (measured liquid cargo tonnage) into a liquid cargo consumption assessment system, which then statistically analyzes the liquid cargo consumption during unsteady voyages. By employing methods such as moving averages and differentiation, this invention eliminates data abrupt changes and large fluctuations caused by unsteady voyages. It automatically identifies the liquid cargo addition and consumption states, statistically analyzes the consumption of each sequence, and ultimately obtains the statistical data on the liquid cargo consumption for the current voyage. This saves crew time from repeated registration and calculations, improves the accuracy of liquid cargo consumption statistics, and provides practical data support for liquid cargo preparation before departure.

Description

Technical Field

[0001] This invention specifically relates to a method for assessing the consumption of liquid cargo during unsteady navigation of a ship. Background Technology

[0002] Before a ship sets sail, the required amount of liquid cargo, such as fuel oil, lubricating oil, and fresh water, is estimated, and the approximate tonnage of the liquid cargo is determined based on the estimate. Currently, this estimation process mainly relies on manually recorded liquid cargo tonnage measurements. However, due to the effects of pitching and rolling caused by the ship's unsteady navigation, there is a significant error between the liquid cargo tonnage measurement sensor readings and the actual values. Directly estimating the liquid cargo tonnage based on manually recorded data does not account for the sloshing effect on the free surface of the liquid cargo during unsteady navigation, resulting in significant calculation errors. Furthermore, the need to manually estimate the time periods for adding and consuming liquid cargo leads to low accuracy and poor timeliness. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method for assessing the consumption of liquid cargo during unsteady navigation of a ship. The method calculates the total consumption within the assessed time period based on the difference between the start and end times of the liquid cargo tonnage change during each consumption period, removes the interference from ship swaying during navigation, and obtains the tonnage measurement data of the liquid cargo during unsteady navigation.

[0004] The objective of this invention is achieved through the following method: a method for assessing liquid cargo consumption during unsteady ship navigation includes the following steps:

[0005] Step 1: Obtain the raw data of the voyage segment collected from the ship condition monitoring equipment, filter out the ship liquid cargo tank tonnage measurement data L containing time information, and load the data into the data analysis software;

[0006] Step 2: Use data analysis software to plot the curve of the liquid cargo tonnage measurement data L changing over time, and perform moving average processing. Set the moving average length N to 1 / 1000 of the total data length. Calculate the moving average for the liquid cargo tonnage measurement data L sequentially. The calculation formula is shown in equation (1):

[0007] Ft=(At-1+At-2+At-3+…+At-n) / n (1)

[0008] Where Ft represents the predicted value at the next time step, n represents the number of sliding time steps, At-1 represents the actual value at the previous time step 1, At-2 represents the actual value at the previous 2 time steps, At-3 represents the actual value at the previous 3 time steps, and At-n represents the actual value at the previous n time steps.

[0009] Obtain the smoothed liquid cargo tonnage data smoothL, and plot the smoothed liquid cargo tonnage data curve.

[0010] Step 3: Identify the time periods for adding and consuming liquid goods.

[0011] Step 3.1: Take the derivative of the smoothed liquid cargo tonnage data, that is, subtract adjacent tonnage data by shifting the difference, and obtain the first derivative curve of the smoothed liquid cargo tonnage data. Obtain the tonnage change at adjacent time points, which is regarded as the liquid cargo tonnage difference quotient LA1.

[0012] Step 3.2: Compare the liquid cargo tonnage difference quotient LA1 with 0 to generate a state logic sequence F. When the liquid cargo tonnage difference quotient LA1 is greater than 0, it indicates a liquid cargo addition state, with a logic sequence value of 1. When the liquid cargo tonnage difference quotient LA1 is less than or equal to 0, it indicates a liquid cargo consumption state, with a logic sequence value of 0. Based on the comparison results, filter out the data in the rising time period of the liquid cargo tonnage curve.

[0013] Step 4: Set a continuous stability time threshold T, select a point in the threshold, and make a continuous stability judgment on the liquid cargo tonnage difference quotient LA1.

[0014] When performing continuous stability judgment, if the continuous stable time length of the data with a value of 1 in the state logic sequence F is greater than the threshold T, the stable segment is retained and the corresponding value in the state logic sequence F remains unchanged. If the continuous stable time length of the data with a value of 1 in the state logic sequence F is less than the threshold T, then the data is considered unstable and the corresponding logic value in the state logic sequence F is changed from 1 to 0, thus obtaining the state logic sequence F1 of the liquid cargo tonnage.

[0015] Then select another point in the threshold and repeat the above judgment process to obtain the second state logic sequence F2. Compare the stability of the state logic sequence F1 and the state logic sequence F2, and select the sequence with higher stability as the continuous and stable state logic sequence F' of the liquid cargo tonnage. The continuous sequence segments with a value of 0 in the continuous and stable state logic sequence F' are numbered sequentially as I, II, III...

[0016] Step 5: Obtain the start and end times corresponding to numbers I, II, III… in the continuous and stable state logic sequence F', and corresponding to the smoothed liquid cargo tonnage data smoothL obtained in Step 2, obtain the liquid cargo tonnage assessment value smoothL at the start and end times respectively. start and smoothL end .

[0017] Step 6: For each numbered sequence, calculate the difference between the assessed liquid cargo tonnage at the start and end times, i.e., smoothL. start -smoothL end The system obtains the liquid cargo consumption statistics for this compartment in this voyage segment, and finally adds up the consumption of each consumption segment to obtain the total liquid cargo consumption of the ship in this voyage segment.

[0018] Preferably, in step 4, when performing continuous stability judgment, multiple points in the threshold are selected for comparison, and the state logic sequence corresponding to the point with the best stability is selected as the continuous and stable state logic sequence F', so as to further improve the accuracy of the evaluation method.

[0019] Preferably, the data analysis software used in the liquid cargo consumption assessment method provided by the present invention includes MATLAB and Python.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] This invention provides a method for assessing liquid cargo consumption during unsteady voyages of ships. First, the tonnage measurement data of the ship's liquid cargo is processed using a moving average to eliminate data abrupt changes and large fluctuations caused by unsteady voyages. Then, the tonnage data after the moving average is differentiated, and based on this, the liquid cargo addition and consumption status is identified according to whether the first derivative value is greater than 0. Next, the interval length of the continuous and stable liquid cargo addition time is set according to the needs of data analysis, and the start and end times of all liquid cargo additions are determined by identifying data with significant changes in the first derivative. Finally, by calculating the difference in tonnage measurement values ​​for each liquid cargo consumption time period, the consumption of this compartment during this voyage is automatically statistically analyzed.

[0022] This invention eliminates data mutations and large fluctuations caused by the ship's unsteady navigation by using methods such as moving average and differentiation. It automatically identifies the liquid cargo addition and consumption status, and statistically analyzes the consumption of each sequence to obtain the consumption statistics of the liquid cargo for this voyage. This saves the crew time of repeated registration and calculation, improves the accuracy of liquid cargo consumption statistics, and provides practical data support for the preparation of liquid cargo before the ship sets sail. Attached Figure Description

[0023] Figure 1 Flowchart of a method for assessing liquid cargo consumption during unsteady navigation of a ship according to the present invention;

[0024] Figure 2 This is a measurement curve of drinking fresh water in an embodiment of the present invention;

[0025] Figure 3 This is a smoothed curve of the drinking water measurement data in the embodiments of the present invention;

[0026] Figure 4 This is the first derivative curve of the drinking freshwater tonnage data in this embodiment of the invention;

[0027] Figure 5 This is a schematic diagram of the state logic sequence F of drinking freshwater tonnage data in an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of the state logic sequence F1 of drinking freshwater tonnage data at T=300s in an embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of the state logic sequence F2 of drinking freshwater tonnage data at T=500s in an embodiment of the present invention;

[0030] Figure 8 This is the distribution of drinking freshwater consumption in an embodiment of the present invention. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0032] like Figure 1 As shown, the present invention provides a method for assessing liquid cargo consumption during unsteady navigation of a ship, comprising the following steps:

[0033] Step 1: Obtain the raw data of the voyage segment collected from the ship condition monitoring equipment, filter out the ship's liquid cargo tank tonnage measurement data L containing time information, and load the data into the data analysis software.

[0034] Step 2: Use data analysis software to plot the curve of the liquid cargo tonnage measurement data L changing over time, and perform moving average processing. Set the moving average length N to 1 / 1000 of the total data length. Calculate the moving average for the liquid cargo tonnage measurement data L sequentially. The calculation formula is shown in equation (1):

[0035] Ft=(At-1+At-2+At-3+…+At-n) / n (1)

[0036] Where Ft represents the predicted value at the next time step, n represents the number of sliding time steps, At-1 represents the actual value at the previous time step 1, At-2 represents the actual value at the previous 2 time steps, At-3 represents the actual value at the previous 3 time steps, and At-n represents the actual value at the previous n time steps.

[0037] Obtain the smoothed liquid cargo tonnage data smoothL, and plot the smoothed liquid cargo tonnage data curve.

[0038] Step 3: Identify the time periods for adding and consuming liquid goods.

[0039] Step 3.1: Take the derivative of the smoothed liquid cargo tonnage data, that is, subtract adjacent tonnage data by shifting the difference, and obtain the first derivative curve of the smoothed liquid cargo tonnage data. Obtain the tonnage change at adjacent time points, which is regarded as the liquid cargo tonnage difference quotient LA1.

[0040] Step 3.2: Compare the liquid cargo tonnage difference quotient LA1 obtained in Step 3.1 with 0 to generate a state logic sequence F. When the liquid cargo tonnage difference quotient LA1 is greater than 0, it indicates a liquid cargo addition state, with a logic sequence value of 1. When the liquid cargo tonnage difference quotient LA1 is less than or equal to 0, it indicates a liquid cargo consumption state, with a logic sequence value of 0. Based on the comparison results, filter out the data in the rising time period of the liquid cargo tonnage curve.

[0041] Step 4: Identification of continuous stable liquid cargo addition time period: Set a continuous stable time length threshold T, select a point in the threshold, and make a continuous stability judgment on the liquid cargo tonnage difference quotient LA1.

[0042] When performing continuous stability judgment, if the continuous stable time length of the data with a value of 1 in the state logic sequence F is greater than the threshold T, the stable segment is retained and the corresponding value in the state logic sequence F remains unchanged. If the continuous stable time length of the data with a value of 1 in the state logic sequence F is less than the threshold T, then the data is considered unstable and the corresponding logic value in the state logic sequence F is changed from 1 to 0, thus obtaining the state logic sequence F1 of the liquid cargo tonnage.

[0043] Then select another point in the threshold and repeat the above judgment process to obtain the second state logic sequence F2. Compare the stability of the state logic sequence F1 and the state logic sequence F2, and select the sequence with higher stability as the continuous and stable state logic sequence F' of the liquid cargo tonnage. The continuous sequence segments with a value of 0 in the continuous and stable state logic sequence F' are numbered sequentially as I, II, III...

[0044] Step 5: Obtain the start and end times corresponding to the continuous and stable state logic sequence F' numbered I, II, III… Based on the smoothed liquid cargo tonnage data smoothL obtained in Step 2, obtain the liquid cargo tonnage assessment value smoothL at the start and end times respectively. start and smoothL end .

[0045] Step 6: For each numbered sequence, calculate the difference between the assessed liquid cargo tonnage at the start and end times, i.e., smoothL. start -smoothL end The system obtains the liquid cargo consumption statistics for this compartment in this voyage segment, and finally adds up the consumption of each consumption segment to obtain the total liquid cargo consumption of the ship in this voyage segment.

[0046] In some embodiments of the present invention, in step 4, when performing continuous stability judgment, multiple points in the threshold are selected for comparison, and the state logic sequence corresponding to the point with the best stability is selected as the continuous stable state logic sequence F', so as to further improve the accuracy of the evaluation method.

[0047] In some embodiments of the present invention, the specific steps for assessing the freshwater consumption of a certain type of ship's drinking water tank using the ship liquid cargo consumption assessment method are as follows:

[0048] Step 1: Obtain the raw data of the voyage segment collected from the ship condition monitoring equipment, filter out the ship drinking fresh water tank tonnage data L containing time information, and load the data into MATLAB.

[0049] Step 2: As Figure 2 As shown, MATLAB was used to plot the curve of the drinking water tank tonnage data L over time, and a moving average was applied. The moving average length N = 195 was set, and the moving average of the freshwater tank tonnage data L was calculated using the formula shown in equation (1):

[0050] Ft=(At-1+At-2+At-3+…+At-n) / n (1)

[0051] Where Ft represents the predicted value at the next time step, n represents the number of sliding time steps, At-1 represents the actual value at the previous time step 1, At-2 represents the actual value at the previous 2 time steps, At-3 represents the actual value at the previous 3 time steps, and At-n represents the actual value at the previous n time steps.

[0052] Obtain smoothed drinking water tank tonnage data (smoothL) and plot the smoothed drinking water tank tonnage data curve, as shown below. Figure 3 As shown.

[0053] Step 3: Identify the time periods when drinking water is added and consumed.

[0054] Step 3.1: Differentiate the smoothed liquid cargo tonnage data, i.e., subtract adjacent tonnage data by offset, to obtain the first derivative curve of the drinking water tonnage data, as shown below. Figure 4 As shown, the change in tonnage at adjacent time points is obtained and regarded as the liquid cargo tonnage difference quotient LA1.

[0055] Step 3.2: Compare the drinking water tonnage difference quotient LA1 obtained in Step 3.1 with 0 to generate a state logic sequence F, such as... Figure 5 As shown, when the liquid cargo tonnage difference quotient LA1 is greater than 0, it indicates the state of drinking water addition, with a logical sequence value of 1; when the liquid cargo tonnage difference quotient LA1 is less than or equal to 0, it indicates the state of drinking water consumption, with a logical sequence value of 0. Data from the rising time period in the liquid cargo tonnage curve is selected based on the comparison results.

[0056] Step 4: Set a continuous stability time threshold T (300s, 600s), and perform a continuous stability assessment on the drinking water difference quotient LA1. If the continuous stability time of data with a value of 1 in the state logic sequence F is greater than the threshold T, the stable segment is retained, and the corresponding value in the state logic sequence F remains unchanged. If the continuous stability time of data with a value of 1 in the state logic sequence F is less than the threshold T, then this part of the data is considered unstable, and the corresponding logic value in F is changed from 1 to 0. Thus, the state logic sequences F1 and F2 for the final drinking water tonnage at T=300s and T=500s are obtained as follows: Figures 6 to 7 As shown, since the duration of each sequence in the state logic sequence F2 is longer and the stability is better when T = 500s, the state logic sequence F1 when T = 500s is selected as the continuous and stable state logic sequence F', and the state logic sequence F2 when T = 300s is discarded. The continuous sequence segments with a value of 0 in the continuous and stable state logic sequence F' are numbered sequentially as I, II, III, IV, V, VI, and VII.

[0057] Step 5: As Figure 7 As shown, the continuous and stable state logic sequence F' is numbered I, II, III, IV, V, VI, VII, corresponding to the start and end times. There are a total of 7 numbered sequences, with corresponding start and end times of (10: 39699), (41698: 47290), (49289: 90723), (92721: 139136), (141014: 149668), (151679: 159030), and (161030: 192798), respectively. Figure 2 The smoothed drinking water tank tonnage data (smoothL) was used to obtain the drinking water tonnage assessment values ​​(smoothL) at the start and end times. start and smoothL end The start and end times of the 7 numbered sequences correspond to... Figure 2 The estimated values ​​for drinking freshwater tonnage in the data are (19.63: 16.22), (19.31: 18.95), (22.11: 17.82), (22.12: 14.48), (19.28: 18.92), (19.98: 18.62), and (21.99: 19.30).

[0058] Step 6: As Figure 8 As shown, for each numbered sequence, the difference between the assessed tonnage of drinking freshwater at the start and end times is calculated, i.e., smoothL. start -smoothL endThe amounts are 3.41 tons, 0.36 tons, 4.29 tons, 7.64 tons, 0.36 tons, 1.36 tons, and 2.69 tons respectively. Therefore, the total freshwater consumption of the ship in this voyage is the sum of the consumption in each voyage, which is 20.11 tons.

[0059] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for assessing liquid cargo consumption during unsteady navigation of a ship, characterized in that: The evaluation method includes the following steps: Step 1: Obtain the raw data of the voyage segment collected from the ship condition monitoring equipment, filter out the ship liquid cargo tank tonnage measurement data L containing time information, and load the data into the data analysis software; Step 2: Use the data analysis software to plot the curve of the liquid cargo tank tonnage measurement data L over time, and perform moving average processing. Set the moving average length N to 1 / 1000 of the total data length. Calculate the moving average value for the liquid cargo tank tonnage measurement data L sequentially. The calculation formula is shown in equation (1): Ft =( At -1+ At -2+ At -3+…+ At - n ) / n （1） in, Ft Represents the predicted value at the next moment. n This represents the number of sliding moments. At -1 represents the actual value at the previous time step. At -2 represents the actual value at the previous two time points. At -3 represents the actual value at the first 3 moments. At - n Representative before n The actual value at that moment; Obtain the smoothed liquid cargo tonnage data smoothL, and plot the smoothed liquid cargo tonnage curve; Step 3: Identify the time periods for adding and consuming liquid goods. Step 3.1: Take the derivative of the smoothed liquid cargo tonnage data smoothL to obtain the first derivative curve of the liquid cargo tonnage data, and obtain the tonnage change at adjacent time points, which is regarded as the liquid cargo tonnage difference quotient LA1; Step 3.2: Compare the liquid cargo tonnage difference quotient LA1 with 0 to generate a state logic sequence F. When the liquid cargo tonnage difference quotient LA1 is greater than 0, it is a liquid cargo addition state, and the logic sequence value is 1; when the liquid cargo tonnage difference quotient LA1 is less than or equal to 0, it is a liquid cargo consumption state, and the logic sequence value is 0. Based on the comparison results, the data for the rising time period in the smoothed liquid cargo tonnage curve were selected; Step 4: Set a continuous stable time length threshold T, select a point in the threshold, and make a continuous stability judgment on the liquid cargo tonnage difference quotient LA1; When performing continuous stability judgment, if the continuous stable time length of the data with a value of 1 in the state logic sequence F is greater than the threshold T, the stable segment is retained and the corresponding logic sequence value in the state logic sequence F remains unchanged. If the continuous stable time length of the data with a value of 1 in the state logic sequence F is less than the threshold T, the data is considered unstable and the corresponding logic sequence value in the state logic sequence F is changed from 1 to 0 to obtain the state logic sequence F1 of the liquid cargo tonnage. Then select another point from the thresholds and repeat the above judgment process to obtain the second state logic sequence F2. Compare the stability of the state logic sequence F1 and the state logic sequence F2, and select the sequence with higher stability as the continuous and stable state logic sequence F' of the liquid cargo tonnage. The continuous sequence segments with a value of 0 in the continuous and stable state logic sequence F' are numbered sequentially as I, II, III, ...; Step 5: Obtain the start and end times corresponding to numbers I, II, III… in the continuous and stable state logic sequence F'. Corresponding to the smoothed liquid cargo tonnage data smoothL obtained in Step 2, obtain the liquid cargo tonnage assessment value smoothL at the start and end times respectively. start and smoothL end ; Step 6: For each numbered sequence, calculate the difference between the assessed liquid cargo tonnage at the start and end times, i.e., smoothL. start smoothL end The statistical results of liquid cargo consumption in the compartments of this voyage are obtained, and finally the consumption of each consumption segment is added together to obtain the total liquid cargo consumption of the ship in this voyage.

2. The method for assessing liquid cargo consumption during unsteady navigation of a ship as described in claim 1, characterized in that: In step 4, when determining continuous stability, multiple points from the threshold are selected for comparison, and the state logic sequence corresponding to the point with the best stability is selected as the continuous and stable state logic sequence F'.

3. The method for assessing liquid cargo consumption during unsteady navigation of a ship as described in claim 1, characterized in that: The data analysis software includes MATLAB and Python.

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