Abstract:To examine the effect of clamping force on the inter-layer gap formed in stacked material drilling, firstly, the drilling deformation state of stacked plates with clamping force was analyzed using elastic shell theory. Further, by finite element method, the drilling deformation model with clamping force was established in consideration of interface contact condition. The accuracy of model was verified by comparing with experimental results of single-plate deformation. Then, the changing process of inter-layer gap was analyzed under different drilling conditions. At last, the experiment was carried out to verify the finite elements analysis results. The results show that, with the increase of clamping force, the inter-layer gap will go through two stages, decreasing rapidly at first and slowly after the turning point. The turning point corresponds to the critical clamping force. To obtain an effective burr height reducing, the following two conditions must be required: Ⅰ) the inter-layer gap D_B corresponding to the turning point should be smaller than the drilling burr height without applying the clamping force, Ⅱ) the clamping force should be higher than the critical force F_B. Besides, reducing the thrust force, or minimum diameter of the clamping ring can reduce the demand clamping force and inter-layer gap size. To enhance the effects of clamping force and minimize inter-layer gap, the thicker plate and the plate with higher modules should be set as the back plate.

Abstract:In order to extract palladium economically, efficiently and environment friendly, lignin is firstly extracted from rice straw by sulfuric acid method, and then the quaternary ammonium rice straw lignin is synthesized through chemical modification with the 3-chloro-2-hydroxy-propyl-trimethyl ammonium chloride (CHMAC). After that, [PdCl₄]^2- was adsorbed by the quaternary ammonium rice straw lignin. The lignin and its derivants were characterized by the scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), respectively. Meanwhile, the effects of pH value, the initial concentration of [PdCl₄]^2-, the adsorption time on the adsorption properties of quaternary ammonium rice straw lignin were investigated. Furthermore, its selectivity for [PdCl₄]^2- was also discussed. The results show that the quaternary ammonium rice straw lignin is porous, rough and irregular with excellent thermal stability below 200 ℃ and infrared absorption peak at 1469 cm^-1 is attributed to the bending vibration of quaternary ammonium ion. Moreover, the optimum value of pH for [PdCl₄]^2- adsorption is 2 and the time of adsorption equilibrium is 8 h. The adsorption reaches saturation when the concentration of [PdCl₄]^2- is 4 mmol·L^-1 with 1.120 mmol·g^-1 of the saturated adsorption capacity. At the same time, the adsorption process could be described by pseudo-second order kinetic equation and adsorption isotherm could be simulated by Freundlich equilibrium adsorption equation, which indicates that the adsorption is chemical adsorption of monomolecular and nonhomogeneous. In addition, the quaternary ammonium rice straw lignin presents excellent selectivity for [PdCl₄]^2- when the concentration of hydrochloric acid is less than 1 mol·L^-1. The lower concentration of hydrochloric acid, higher initial concentration of [PdCl₄]^2- and longer adsorption indicate the better of adsorption capacity and selectivity.

Abstract:The systems with interval time-delay appearing in state variable have wide application, and can be used to describe a class of networked control systems. The stability analysis and the state feedback controller design are investigated for linear discrete-time systems with interval time delays. In order to investigate the stability, a new Lyapunov-Krasovskii functional is proposed by introducing the double summation and triple summation. In order to estimate the difference of the Lyapunov-Krasovskii functional, the Abel lemma based finite sum inequality technique and the time delay segmentation method are used as tools, and thus a sufficient condition is presented for the asymptotic stability of the considered systems in terms of linear matrix inequalities. Compared to the traditional Lyapunov functional, since the proposed Lyapunov-Krasovskii functional contains more information on delays, and the approach for estimating the difference does not involve model transformation, thus the presented sufficient condition for the asymptotic stability of the system is less conservative. In addition, compared with the previous free-weighting matrix method there exist less feasible matrix variables in the current method. Thus, the computational load can be effectively reduced. According to the derived stability criterion, a design approach for non-memory state feedback controllers is presented in terms of linear matrix inequalities, and thus has good numerical stability. Finally a numerical example is employed to illustrate the effectiveness of the methods proposed in this paper.

Abstract:A Visual Map can be seen as an image database with rich location information. All images or image features stored in this database have their corresponding location information. An accurate localization needs a large image database, but building a large database must be laborious and time-consuming. In order to solve this problem, a method based on Optical Flow Technique is proposed to establish a Visual Map. The accuracy of Optical Flow algorithms is always influenced by the difference of indoor illumination and lateral deviation of optical flow caused by turning of the cameras. A method to improve optical flow algorithm is proposed and the new algorithm is used to calculate the displacement of image sequences to acquire location information of the camera and each picture. The experimental results show that the probability of localization error less than 1 meter and 2 meters is 26% and 70%, respectively. Compared with traditional visual indoor localization system, using optical flow algorithm to build a visual map is much more convenient and time-saving, although the positioning accuracy of the proposed method is slightly worse than the traditional method. Although the performance of the proposed method is similar to the video stream method, it needs fewer sensors to build image database and can be used in more complicated environment. Overall, the proposed method will perform well in indoor visual localization systems especially in large buildings and changeable places.

Abstract:In order to effectively control the welding seam formation during electron beam welding to meet the welding structure requirements, the physical process of molten pool during EBW was analyzed. A three-dimensional EBW model was employed to simulate the molten pool in full penetration welding based on finite volume method (FVM). The molten pool behavior and rules were discussed. The simulation results showed that when the keyhole is formed by electron beam welding, the velocity and direction of the liquid metal in the molten pool changes rapidly, and the maximum flow rate can reach 10 m/s.The molten pool was vibrated violently by recoil pressure during the welding process. The heated liquid metal away from the keyhole driven by Marangoni convection to increase the width of molten pool. The width and longitude of molten pool were stable at about 35 ms and 90 ms, respectively. After solidification, the weld reinforcement and the shrink appeared at the top surface and the reverse side. The bead shape abstracted from the simulation and experimental result showed similar evolution. Moreover, according to the analysis of fluid flow in molten pool, it can also be concluded that the driven force of recoil pressure was much greater than that of the gravity and surface tension.

Abstract:Frequency estimation algorithm for Minimum Shift Keying-Type(MSK-Type) signals is usually based on maximum likelihood theory. However, the algorithm is complex, and it is not practically realized in engineering. So the frequency synchronization for MSK-Type signal mostly adopts nonlinear methods such as delay-multiplication and 2P-Power algorithms. But these feedforward structure of non-data aided algorithm applies only to full response MSK-Type signal, and due to the nonlinear process of multiplying, these algorithms introduce large amounts of self-noise, so that it leads to poor synchronization performance. In order to solve the problem of lower accuracy and narrower application range and unpractical realization in engineering for the existing nonlinear algorithms, an improved algorithm based on delay-multiplication frequency synchronization algorithm is proposed in this paper. After different power nonlinear processing on the MSK-Type signal with partial response and full response, the improved algorithm eliminates the effects of self-noise in the delay-multiplication algorithm. Compared with the original algorithm, the estimated accuracy for the frequency offset is improved about 5dB, and at the same time, the application range is extended to the partial response MSK-Type signal. The improved algorithm enlarges the application range and it is easy to be implemented in engineering.

Abstract:In order to improve overall performance of automotive sheet of Al-Mg-Si series alloy, three groups of alloy ingots were prepared by casting method, then, 1 mm thick alloy sheets were achieved through homogenization, hot rolling, intermediate annealing, cold rolling. After solution treatment at 560 ℃ for 30 mins, immediately pre-aging at 100 ℃ for 8 h, and then stored at room temperature for 14 days to simulate the process of transportation and storage. Finally, the alloy sheets baked hardening at 185 ℃ for 20 mins after 2% deformation. The microscopic structure of alloy was observed by metallographic microscope; its texture was analyzed by scanning electron microscope equipped with electron back scattering diffraction, and the mechanical property was tested by electronic universal testing machine. The effect of different Mg/Si ratio and high Zn content on recrystallized structure and texture, bake hardenability and corrosion sensibility were studied. The results indicated that the recrystallized structure of alloy with equal Mg/Si ratio was smaller and more uniform. The average size of grains was 190 μm. The cube orientation {001}<100> was smaller, while the P orientation {011}<122> was larger. Whereas the local grains of alloys with high Mg content and high Si content were coarse, the cube component {001}<100> was larger and the P component {011}<122> was smaller. The strength of alloy with equal Mg/Si ratio was higher, accompanied by good bake hardenability after pre-aging. The paint-bake hardening increment was 107 MPa. After bake hardening, more Zn atoms were diffused into grain boundary, enhancing the response of micro-current. The resistance of corrosion sensibility was poorer than that of high Mg content and high Si content alloy. The depth of corrosion was 121 μm.

Abstract:Until recently, TCAR (Three-Carrier Ambiguity Resolution), CIR (Cascading Integer Resolution) and LAMBDA (Least-squares Ambiguity Decorrelation Adjustment) are the wildly used method for integer ambiguity resolution. TCAR and CIR, both taking advantages of the wide-lane combination which is easier to fix the integer ambiguity, and the narrow-lane combination which can reduce the noise more efficiently, are currently used as two common integer ambiguity resolutions. However, either TCAR or CIR performs a lower probability of resolution success in comparison with LAMBDA, even requires a pre-set admissible ambiguity transformation. To deal with this problem, a method based on a combination of wide and narrow lane LAMBDA integer ambiguity resolution, in terms of Beidou differential positioning problem, is proposed. On the basis of LAMBDA, this method employs the advantages of both the wide-lane combination and the narrow-lane combination. In this method, the integer ambiguity of narrow-lane combination is constrained by using the wide-lane combinations, which conducts a fast integer ambiguity resolution, while a high accuracy positioning is obtained by using the narrow combination, which suffers low noisy affect. The performance of the method was evaluated in a test site on the roof of Beihang University using tri-frequency data from BeiDou. The result shows that this method can achieve a 3 mm positioning accuracy at a shorter convergence time when compared with the convergence time of narrow-lane combination.

Abstract:To solve the problem that the current spaceborne memory cannot support parallel storage of multi-channel high-speed data effectively, this paper proposes two methods. To satisfy the requirement of receiving high-speed payload data, this paper analyzes the throughput bottleneck of NAND Flash-based solid-state memory, and proposes a four-stage pipeline operation and bus parallel expansion scheme according to the inherent write operation characteristics. To meet the needs of parallel storing multi-channel data and the continuity of pipeline operation, this paper analyzes the deficiencies of the data cache methods which use RAM (Random access memory) and SRAM (Static Random Acess Memory), and proposes a scheduling scheme using high-speed caching and cooperative storing, which is based on SDRAM (Synchronous Dynamic Random Access Memory). Through the model simulation and the prototype function verification, we verify that the proposed scheme can effectively support parallel reception of the 4-way high-speed payload data and the autonomous scheduling storage of solid state memory, and the throughput rate of memory can reach 1.2 Gbps, which satisfies the demands for storing the multi-channel high-speed payload data on spaceborne memory in the future.

Abstract:Focusing on the interpretability problems of image classification models based on deep convolutional neural network, a visualization method for improving the feature space of model is proposed by evaluating the potential expressiveness of model feature space. Given any pre-trained deep model, firstly the method generates an image by the normalized operation of the gradient in the back propagation, which maximizes activation the class score, and then uses the momentum of the stochastic gradient descent training strategy for back propagation to the original input image. The conventional regularization technique cannot adjust the feature space of the model. Therefore, the spatial pyramid decomposition method is proposed on the basis of the existing regularization method. By constructing the multi-layer Laplacian spatial pyramid, the low frequency component of the target image feature space is promoted, combined with multi-layer Gaussian spatial pyramid to adjust the high-frequency components of its feature space to obtain a better visualization effect. By limiting the region of visualization, it is proposed to use the class activation map to suppress the context-free information, which can further improve the visualization effect. The visualization experiments are performed on the different classes of the model and the individual neurons of the convolution layer. Results show that the proposed method can achieve better visualization effect in different depth models and different visualization tasks.

Abstract:Focusing on the problem of lack of independent cache module of original iSCSI target controller, we introduce a fusion cache mechanism based on flash memory called FusionCache into the iSCSI target software to further improve the overall performance of the storage area network. FusionCache uses flash memory and DRAM to form a unified fusion cache architecture. The flash memory acts as DRAM's expansion space, and DRAM is divided into cache block metadata area (metadata cache) and front-end buffer area (front cache). The metadata cache manages cache block metadata based on radix tree in order to accelerate the cache block searching; the front cache tallies and predicts the access popularity of the cache block based on regressing fitting model, and absorbs the impact of massive writes on flash memory to ensure that only the hot data is allowed to enter the flash memory. FusionCache uses the improved LRU algorithm to do cache replacement. Besides, it takes iSCSI session's state into account during write-back. The experimental results show that: FusionCache is able to reduce access to backend disk devices, and improve I/O response speed. FusionCache reduces I/O access latency by 33% and 60%, and improves throughput by 25% and 54%, compared to cache mechanism with only DRAM and original iSCSI target, respectively. Compared with Flashcache proposed by Facebook, FusionCache improves throughput by 18% and reduces latency by 27%. FusionCache also has a good read cache hit rate. Besides, FusionCache reduces write amount of flash memory, thus extends its life. FusionCache provides good efficiency of network storage and reduces cost.

Abstract:Parameter and tolerance design are used to reduce the cost of production and improve the robustness of product. We consider the effects of model parameter uncertainty and quality loss function coefficient, and propose a parameter and tolerance economic design approach based on confidence level and entropy method. The proposed approach consists of parameter design stage and tolerance design stage. In parameter design stage, we obtain the best design variables through maximizing the confidence level of quality characteristics. In tolerance design stage, we get the quality loss function coefficient through entropy method, and then obtain the best tolerances through minimizing the total cost function which is composed of quality loss cost and tolerance cost. In this paper, we have analyzed the amine addition experiment of resin production process and studied the influence of temperature, agitation and rate of addition on the viscosity of resin systematically. Experimental results indicate that the optimal design variables and their tolerance values obtained by the proposed approach minimizes the effects of model parameter uncertainty while reducing the quality lost and tolerance cost.

Abstract:The combustion process of pulverized-coal is widely used in different industries as a supplier of energy. In order to investigate the influence of heating rate on the combustion kinetics of pulverized-coal, the study of combustion pulverized-coal at different heating rates (20 ℃/min, 25 ℃/min, 30 ℃/min, and 35 ℃/min) was conducted by thermogravimetric analysis. The results show that the entire combustion process indicates a thermal hysteresis phenomenon with heating rate increasing. According to the characteristics of the pulverized-coal combustion, the combustion process from ignition temperature to burnout temperature is divided into two regions according to the temperature where the reaction rate curve reaches the valley value. Then, interfacial chemical reaction model and internal diffusion model are successfully applied to describe the two regions of combustion process. The obtained corresponding kinetic parameters show that the kinetic compensation effect between activation energy E_ai and pre-exponential factor A_i for different heating rates is expressed as ln A_i=aE_ai+b and the influence of heating rate β on activation energy E_ai can be described as E_ai=△E_aln β_i+E_a0. Later, the Arrhenius equation (ln k_i=-E_a0/RT+ln A₀) is modified as ln k_i=-E_a0/RT+△E_a(a-1/RT)ln β_i+ln A₀ to describe the influence of heating rate β on the rate constant k of pulverized-coal combustion. Finally, the extrapolation reliability of the modified Arrhenius equation is validated by the experimental data at different heating rates(10 ℃/min, 15 ℃/min, 40 ℃/min, and 45 ℃/min). Therefore, the modified Arrhenius equation is not only the most expedient way to depict the combustion kinetic at different heating rates, but also provides extrapolation reliability over a broad range.

Abstract:In order to prevent the methane disaster in coal mine effectively and obtain the reasonable parameters of promoting methane extraction by coal seam water infusion, the 2103 working face of Changcun coal mine was investigated as an example. Using the coupling of VOF model of Fluent software and porous medium model, promoting methane drainage by coal seam water infusion and its influence factors was simulated based on the multi-phase porous flow theory. The comparison shows that the simulation results were basically consistent with the measured data. The results are detailed as follow. The gas content in coal seam gradually decreased with the increase of the radial distance from centerline of water injection hole and it increased with the increase of the radial distance from centerline of gas drainage hole. During drainage period before water injection, the scope of drainage increased gradually and gas flow in drainage hole decreased quickly at first, and then decreased slowly. During the stage of water injection, the scope of drainage increased and water injection flow decreased gradually, while gas flow in coal seam and gas flow in drainage hole also increased gradually over time. And after water injection, the coverage area of pressure water continued to increase, while gas content in coal seam and gas flow in drainage hole both declined little by little over time. The opportunity, time, pressure, layout, pressure, space between boreholes and the way of water injection are the 6 main factors which influence the effect of promoting methane extraction by coal seam water infusion. It can achieve the best effect when intermittent water injection was carried out for 10 days under the pressure of 8 MPa water injection according to the way of one injection and one pumping and arranging the drilling holes spacing at 5 m after 20 days of the methane drainage.

Abstract:Detailed research focusing on the inter-cluster routing for wireless sensor networks (WSNs) is given first. The energy consumption imbalance problem and its cause are presented through a simple example. The paper points out the fact via an example that, the selfish of each cluster head leads to the imbalanced distribution of data flow and the data distribution imbalance then results in energy consumption imbalance. Subsequently, the non-cooperative game model aiming at regulating the behavior of the cluster heads is proposed. The Nash Equilibrium Point (NEP) of the game model is then obtained and proved. According to this game model, an energy-efficient Inter-cluster Routing algorithm based on Non-cooperative Game (EIRNG) is presented, which is the key contribution of the paper. Finally, extensive simulation experiments are conducted and the horizontal and vertical contrast in terms of energy efficiency and network performance are also made. The results show that the cluster heads tend to dissipate energy evenly via determining the optimal amount of the traffic based on a balance factor θ_i. Compared with the classic clustering routing PEGASIS and the authors' former work EEREG, the network lifespan can be extended by 74.1% and 8.6% respectively. Therefore, the proposed EIRNG can improve the energy efficiency and the network performance of the network effectively.

Abstract:To accurately obtain the optimal mix proportioning of cemented tailings backfill (CTB) for an iron mine, the slurrying water property, the weight ratio of tailings to binder (T/B) and the mass concentration of CTB were selected as influencing factors, and the compressive strength, the slump and the bleeding rate of CTB were selected as performance parameters. Based on the response surface-desirability function coupling theory, Box-Behnken design method was used to carry out thirteen groups of experiments with different mix proportioning. Then the effects of influencing factors on performance parameters of CTB were assessed and response surface functions of performance parameters were established. The results show that the slurrying water property has little effect on response variables. T/B has an extremely significant effect on uniaxial compressive strength after 28 days curing time of CTB, and slump is affected by both mass concentration and T/B at a more significant level. Moreover, T/B, mass concentration and their interaction have an extremely significant effect on bleeding rate. The optimal mix proportioning is that the slurrying water resource is seawater; T/B is 8.44 and the mass concentration is 72%. Under such conditions, the predicted values of response variables are 2.00 MPa, 27.15 cm and 7.35%, respectively, which are in perfect agreement with the confirmatory experimental results. The results of this research provide a more comprehensive engineering approach to CTB mix proportioning.

Abstract:In order to reduce the hardware resource consumption and output delay in the conventional pipeline CORDIC (Coordinate Rotation Digital Computer) algorithm, a LUT-omitted CORDIC algorithm is proposed on the basis of the three-stage CORDIC with look-up table (LUT). The proposed new algorithm adopts 4 iterations of shifter-adder instead of LUT to reduce the register consumption apparently, and merges some iterations to decrease the output delay effectively, and guarantees the output resolution by using a combination of Binary to Bipolar Recoding (BBR) and angle range folding. The improved algorithm is specifically implemented using Verilog HDL on ISE 14.2 software platform and synthesized using XST tools, and is modeled to analyze the output errors through MATLAB. Simulation experiment results show that the register resource consumption of the new algorithm, producing sine/cosine effectively, is reduced by about 74.42% compared with the conventional one, while the output width is set to 16 equally. The computing clock periods are decreased by 68.75%, and the resolution is also improved obviously. Compared with the three-stage algorithm, the consumption of register is reduced by about 43.3%. The proposed algorithm has some advantages such as brilliant real-time performance, high resolution, and low consumption. And it is more applicable for modern digital communication systems that demand for high speed and promising real-time performance.

Abstract:The corrosion behavior of 20# steel was studied under CO₂/H₂O two phase plug flow condition using self-designed experiment device. The corrosion rate, corrosion appearance, the composition of corrosion products and the structure characteristics of film were investigated through weight loss method, scanning electron microscope (SEM), energy disperse spectroscopy (EDS) and X-Ray diffraction (XRD), respectively. The results show that the trend of corrosion rate first slightly decreases followed by a rapid increase, and then dramatically decreases with the increasing of corrosion time. The maximum (2.074 6 mm/a) and minimum (1.898 8 mm/a) value reached at 4 h and 8 h, respectively. The corrosion characteristics of corrosion products on the bottom pipe wall by the beginning of the single layer of loose flocculent and tine needle product change into double films of corrosion product gradually. The outer layer with micro-crack is loose, but the inner is relatively dense and its density is increasing with time. The EDS analysis results confirm that the inner dense layer belongs to rich iron product because the Fe content is higher than that of outer layer, and the content of C/O elements in outer loose layer is relatively high. At the same time period the corrosion products at the top wall of pipe are a zonal distribution along the vertical direction of flow, and the bulky loose particles at initial stage gradually transform into crystal grain with regular arrangement. Corrosion products mainly consist of Fe, C, O and the composition mainly includes Fe₃C, FeCO₃, Fe₃O₄ and FeOOH.

Abstract:To satisfy the real-time precise positioning requirement of single-system single-baseline with dual-frequency data, a novel approach based on dual-frequency uncombined data is proposed. The single-system single-baseline and dual-frequency uncombined Real Time Kinematic (RTK) is realized based on inter-station-inter-satellite carrier phase and pseudorange measurement model. Based on the analysis of the residual errors of the double difference model, the state vector is established, and then the state prediction equation and the measurement equation are derived. The real-time transformation matrix of the state vector is established at each epoch, and the weights of observations including pseudorange and carrier phase are adjusted by a random model. Then extended Kalman filter is used to estimate the position of the user receiver. The approach is tested with several groups of medium-range and long-range single-baseline data which are the actual collection of satellites in the experiment. The effectiveness of the approach is verified by examining the three-dimensional errors of the positioning result as well as the success rate of the ambiguities. It is shown that when the baseline is 135.6 km, the positioning accuracy of the proposed approach can reach the centimeter level with the 97.3% success rate of the ambiguities, and the CEP95 positioning errors of east and north and sky directions are 1.35 cm, 1.84 cm, 7.08 cm respectively. This approach makes full use of the advantages of differential technology to eliminate the relative errors independent of distance and effectively avoid the noise caused by the linear combination of the multiple frequency measurements and can satisfy real-time precise positioning for medium and long single-baseline.

Abstract:Composite materials with its superior performance are more widely used in the field of shipbuilding. As a typical engineering structure, steel-composite with heterogeneous property has the dynamic characteristics different from that of a single homogeneous system. As the actual structure is generally more complex, it is difficult to directly determine the composition of the subsystems involved in vibration or noise radiation in the composite structure. In order to obtained the subsystem that are involved in the vibration of the composite structure, based on the analysis of the master-slave vibration mode and damping dissipation mechanism of heterogeneous composite system, combining with statistical energy analysis principle on the loss factor classification description, the damping law of the composite system was analyzed. The loss factors and the energy proportion of the dominant vibration subsystem of steel-composite system were calculated and compared. The results show that after eliminating the effects of radiation loss and boundary loss, the internal loss factor of the heterogeneous composite system close to the material loss factor of its dominant vibration subsystem in magnitude, and between each subsystem of material loss factor value. The modal recognition of a typical combination system is completed, and the feasibility of using the loss factor composition rule to identify the dominant vibration subsystem is verified. The deficiency of complex non-homogeneous composite structure in modal recognition is made up.

Abstract:In order to effectively detect whether the chip is inserted into the hardware Trojan circuit during the design and manufacturing process, a method is proposed to increase the transition probability of the circuit nodes by inserting 2-to-1 MUXs in the chip design stage. The main input of the candidate node whose transition probability is lower than the transition probability threshold is inserted into the MUX to improve the transition probability of the relevant nodes, so as to realize acceleration of hardware Trojan detection in the circuit. The optimization of the insertion algorithm is realized by analyzing the fan-out cone and logic topology, and the node with the greatest influence on the transition probability of the whole circuit is selected as the candidate node, thus the number of MUXs insertion is reduced. Meanwhile, the critical path delay limit is increased to avoid the critical path delay of the circuit exceeding the preset threshold. The input terminals of the pre-designed hardware Trojan circuit are inserted into the nodes with small transition probability in the circuit, and the excitation signal is inputted to the input terminals of the circuit to analyze the change of the circuit's transition probability and the activation probability of the hardware Trojan circuit before and after the MUX insertion. The experimental results of the ISCAS'89 reference circuit show that the number of nodes whose transition probability is less than the transition probability threshold in the circuit is significantly lower; the probability of the inserted hardware Trojan being activated is significantly improved; the increased percentage of circuit critical path delay is controlled within a preset scale factor.

Abstract:Existing test results show that the continuous rotation of principal strain axis in cyclic deformation leading to actuation of multi-slip systems which hinders the forming of stable dislocation substructures inside the material, during nonproportional cyclic loading. As a result, the stress response under nonproportional loading will be larger than that under proportional loading. In other words, the material shows additional hardening upon nonproportional cycling. Therefore, a new constitutive model for modeling stabilized cyclic stress-strain response is proposed to consider the effect of nonproportional additional hardening based on the general form of stress-space incremental plasticity relation. In the hardening rule of the proposed model, the evolution of the back stress is simulated by introducing the nonproportionality factor, f_np, and the additional hardening coefficient, α_np, into the basic Armstrong-Frederick model. The consistency condition is enforced to obtain the relationship between the back stress and plastic modulus. Besides, a new algorithm is proposed to calculate the nonproportionality factor on the basis of the minimum normal strain range. Procedures to determine the minimum normal strain range are presented for the general multiaxial loadings. In the proposed model, the effect of nonproportional additional hardening is reflected by introducing f_np and α_np, not only on the shape of the loading path, but also on the material and its microstructure. Meanwhile, the two drawbacks of the Armstrong-Frederick model are overcome. The proposed model requires only five material constants for estimating the stabilized response. Comparisons between test results of S460N steel and 304 stainless steel and model predictions under various loading paths show that the proposed model predicts relatively accurate stress responses under both proportional and nonproportional loading paths.

Abstract:According to difficult fault localization of virtual reconfigurable circuits (VRC) and large test times of traditional fault localization technology, a novel rapid fault localization technology of VRC based on improved binary search is proposed. When the scales of VRC are no more than two rows (or two columns), fault PE can be located line by line (or column by column). When the scales of VRC are larger than two rows and two columns, the fault dubitable area of programmable elements (PE) can be confirmed by one row-test and one column-test, and then the test direction can be confirmed through the number of rows and columns of fault dubitable area. Eventually, fault dubitable area can be divided equally in the test direction, and two parts can be configured based on the theory of row-test and column-test. Faults can be located by "AND" operation of two parts. All faults PE can be located until fault dubitable area can not divided two parts. Compared with traditional VRC fault localization technology, the test performance analysis of fault localization proves that continuous distribution trouble-free PE can be detected and isolated by proposed VRC fault localization technology, and test area can be narrowed quickly. The test number of faults localization can be reduced, and the maximum test numbers are smaller than former. The average decrement of single and dual fault localization test number is more than 50%. The feasibility and validity of proposed improved rapid fault localization technology are proved, and it has definite generality and engineering application value.

Abstract:According to the data of radar cross section (RCS) under different polarization modes difficult to accurately measure aircraft stealth performance in each angle domain, an evaluation method based on the moving-polynomial smoother algorithm and detection probability model is proposed. Firstly, the circumferential RCS data of HH polarization and VV polarization is treated smoothly to decline relative error of RCS polarization by setting smooth window. Then, radar detection probability and detection probability error of smooth data are calculated based on the single-hit detection and the incoherent integration detection. Combined with two kinds of error conditions and according to the principle that the best moving-polynomial smoother is that relative error of RCS polarization is a minimum with the undistorted raw data information, and the optimal incoherent integration detection effect is that the error information of detection probability in each angle domain is reflected as much as possible. The optimal combination solution is made up of the smooth window and incoherent integration pulse is defined. Finally, the optimal simulation results of the smooth RCS data and detection probability are obtained by using traverse comparison, and then aircraft stealth performance is analyzed quantitatively and evaluated effectively in each angle domain. Simulation results show that incoherent integration detection probability of the smooth RCS data could evaluate aircraft stealth performance in key angle domain, and the assessment effect is the best when the combination solution is (10, 10).

Abstract:In the practice of enterprises management, inventory is a double-edged sword. Adequate inventories can gain more profit and reputation for enterprises. But overstock will add inventory expenses, increase cost, reduce profit and go against management level for enterprises. On the contrary, low inventories can cause the decline of service level and affect the sales profit and reputation. This paper mainly studies the inventory decision problems of the retailers under the condition of variable lead time and partial admission for delay in delivery, and analyzes it when service level is bounded and the demand follows free distribution. The dissertation adopts the accurate solution method and the Minmax method to find the optimal order quantity respectively. In the end, it analyzes the differences of the optimal solution under different inventory models, and takes sensitivity analysis in service level and safety factor into consideration, through which the enterprises can know the lost cost for the 1% increasing of the service level when the service level and lost cost are taken into account at the same time. If the retailer only consider the service level, not stock-out, the retailer will not know how much is their loss of the cost for service level declining. It must be considered not the lost cost but also service level to find the best combination of the two points, so that the enterprise can adjust the strategy in the competition, to gain competitive advantage.

Abstract:In the manufacturing process, environmental factors such as tasks, natural conditions, power levels, etc., restrict the state change of objects and their relationships. Intelligent manufacturing units need to adaptively understand and judge events and complex situations under different context constraints, and a adaptive situation identification method based on complex event processing is proposed naturally, to make real-time optimization decision reasonable. In view of the phenomenon that the influence of context constraints on event discrimination is neglected, a context-aware hierarchical event model is built, and new operators of events such as contemporaneity, context and collaboration are given, while manufacturing situation model and aggregation process are proposed. Aiming at the shortage of generating method on situation model in knowledge base, the mapping association between an object and environment data is established firstly, and such sensed information is transformed into context based events. Integrating the distance calculation of ordinal, nominal variable and adaptive entropy weight method, a improved mixed clustering method is put forward to deal with the diversity and relevance of complex event instance attributes, providing service support for real-time situation identification. Finally, 4 real data sets and 1 simulation data set of are employed for manufacturing process. Experiment results have verified the validity and adaption of the proposed model and method in large-scale problem, and expounded that context factors can significantly improve the accuracy of event judgment and situation recognition in complex manufacturing applications.

Abstract:The development of mobile Internet and wireless communication technologies promote heterogeneous wireless networks (HWNs), in which a variety of wireless networks coexist and coverage overlap. The differences between various wireless access technologies and single network cannot meet all the requirements of users. Consequently, it is inevitable for the integration of HWNs. The access selection as one of the key technologies of HWNs has become a research hotspot. Based on analyzing the infrastructure of HWNs and the concepts of the access selection, this paper focuses on the classification and detailed comparative analysis of the access selection algorithm. Simultaneously, the existent problems are summarized, and the future research directions and challenges are presented.