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Traditional power distribution systems in ship field usually adopt power breakers, contactors, relays and fuses as power distribution devices, thus result in low fault response and lack of current-limiting, so loads with high current spikes when started may result in large voltage drop on the DC power bus or misoperation of the power distribution branch, moreover, short-circuit may bring great damage to the whole power system. In this paper, a smart power distribution equipment is proposed, to automatically distinguish different load type and state, realize current-limiting when large capacitive load is started and cut off the power distribution branch whenever short-circuit occurs. This technique greatly increases the smart management capability of the power system. The feasibility and effectiveness of this technique is verified by the experiments carried out on a 24V/2kW prototype.

Grasping a non-cooperative “customer satellite” with a robotic arm is a challenging task for on-orbit services of spacecraft since the collision between the robot and the target is inevitable and the dynamic behaviors of the two objects are hard to control after the collision. To grasp successfully, the contact between the space robot and the target is hoped to be maintained after the collision. In this paper, the contact control problem for grasping a non-cooperative satellite is studied. First, to simulate the contact conditions as realistic as possible, the multibody dynamics, the modified Hertz contact, and the contact detection theory are employed to establish a grasping dynamics model. Then, based on the study on the dynamic behavior of the two-ball collision problem, a hybrid control scheme with damping and attitude tracking controllers is proposed. By this scheme, the control goal, i.e. maintaining the contact between the robot and the target, can be realized after multiple collisions. Finally, numerical simulations are performed to validate the proposed control scheme, and the results demonstrate its effectiveness in grasping a non-cooperative tumbling satellite.

The relative pose estimation between the chaser and the non-cooperative target is a significant prerequisite for performing on-orbit servicing (OOS) missions. The chaser could design the close-range rendezvous trajectory to approach the non-cooperative target only when the relative pose parameters are obtained effectively and efficiently. In this paper, a pose estimation scheme is designed to obtain the relative pose parameters between the chaser and the non-cooperative target coated with multilayer insulation material (MLI). The scheme utilizes a time-of-flight (TOF) camera to acquire 3D point clouds of the non-cooperative target, and uses the iterative closest point (ICP) method to achieve the point cloud registration between every two frames. Aiming at decreasing the non-systematic errors caused by MLI in the data acquisition of the TOF camera, the corresponding point median filtering approach is adopted to filter out the bad corresponding point pairs generated in the ICP method. A semi-physical experiment is carried out to evaluate the performance of the proposed scheme, the result of which shows that the proposed scheme could notably improve the accuracy of pose estimation of the non-cooperative target, meanwhile the computational efficiency is also ensured.

Graph-based signal processing (GSP) is an emerging field that has been used in many domains. Getting inspiration from the successful applications of GSP in signal filtering and image processing, in this paper, we demonstrate how GSP can serve as a feasible approach to non-intrusive appliance load monitoring (NALM). Specifically, NALM means disaggregating household's gross energy consumption down to single appliances through purely software solutions. Since NALM was proposed over 30 years ago, it has got a lot of attention. However, despite the fact that many solutions has been proposed, the majority of approaches can't work well without training and are prone to appliance variations requiring re-training on a regular basis. In this paper, we tackle this challenge by applying a GSP-based NALM approach that can perform well with no training. This algorithm uses GSP three times, which represents the datasets of active power measurements with 1 min resolution using graphs to perform adaptive thresholding, signal clustering and feature matching respectively. Simulation results using publicly available REDD dataset demonstrate the feasibility and potential of the GSP for NALM.

To understand the power line communication signal characteristics and overcome the shortcomings of traditional linear models and statistical parameters, which can't well describe non-stationary and nonlinear characteristics of power line communications signal, the fractal theory is introduced to understand the fractal characteristics of broadband power line communication signal (BB-PLC). This paper presents four methods for studying fractal, namely, rescaled range analysis, variance-time plot method, periodic diagram analysis and wavelet-based method. After verifying the obvious fractal characteristics, we perform fractal analysis using the measured signal at different frequencies and times, revealing self-similarity of the time series. Experimental results show that the power line communication signal has obvious fractal characteristics. All these results can provide reference for broadband power line channel modeling technology.

In this paper, a microstrip diplexer with compact size and good output isolation is proposed. This diplexer consists of two types of folded net-type resonators which have the same size but different resonance frequencies for composing the diplexer. Good selectivity and stopband suppression properties are achieved. For validation, the diplexer operating at 2.45/3.55 GHz is implemented and the area of the circuit is only 13.2mm × 16.7mm or 0.17λg × 0.22λg.

By using the finite element method, the propagation of Lamb waves in sandwich phononic crystal plates is investigated. This structure is composed of a two-dimensional phononic crystal plate coated with two homogeneous substrates on both surfaces. The phononic crystal plate is constituted by a square array of elastic cylinder embedded in a solid matrix. It is shown that some complete band gaps are opened by changing the thickness of the phononic crystal plate, and that the width of the first band gap becomes larger as the thickness increased. The influence of the thickness and material properties of the substrates on the width of the complete band gap is discussed as well. It is noted that the thickness of either phononic crystal plate or substrates plays a key role in tuning the band gaps of the sandwich phononic crystal plates.

Through a systematic study of bulk cargo inventory process, the article discovers the change law of bulk cargo inventory cost with the moving weighted average method, analyses the primary causes of financial variance from the view of planned cost, and then proposes a solution to the question of how to analyze and control financial variance.

A cost model of oil product secondary distribution system is proposed for the multi-variety oil product. Transportation assignment optimization of oil product secondary distribution with multiple oil depot distribution centers and multiple oil stations are studied. A transportation assignment scheme is obtained by the table-manipulation method. Total transportation cost can be optimized by the transportation assignment scheme. Based on this scheme, the total transportation cost of oil product secondary distribution can be calculated. Finally, a numerical example is given to verify the effectiveness of this scheme.

A cost optimization model of supply chain distribution system is proposed for a single product. The demand per day and the lead-time are assumed to be stochastic variables. Cost optimization problems of distribution systems with multiple manufacturers, an intermediate warehouse and multiple distributors are studied, under the restricted service level that the distributor must meet customer's demand. The model considers ordering cost, replenishing goods cost, inventory holding cost and in-transit holding cost, transport cost and shortage cost synthetically. Algorithm of optimal order quantity is given under the constraint. Finally, a numerical example is given to verify the effectiveness of this model.