Search

There are six deserts and sandy lands in the central and western part of Inner Mongolia, which is one of the main sources of sandstorms in China. In most areas, the surface is dry, the precipitation is low and the wind is strong in winter and spring. The analysis and study of sandstorms in this area is of great significance to the study and prediction of sandstorms in China. Based on the comprehensive analysis of the research status of sandstorms at home and abroad, the application of convolution neural network to classify satellite cloud images and establish prediction models of sandstorms are relatively few. The convolution neural network algorithm based on transfer learning is used to classify infrared satellite cloud images to establish Sand-dust Storm Prediction model, and the prediction accuracy of sand-dust storm prediction model established under different learning strategies is compared in the paper. The results show that the model training speed is fast and the accuracy and generalization ability of the model are improved by using the parameter migration initialization network in transfer learning. The Sand-dust Storm Prediction Model Based on the convolution neural network algorithm of transfer learning has a higher accuracy in predicting the occurrence of sand-dust storm and the change of learning strategies has an important influence on the prediction accuracy of sandstorm prediction model.

This paper presents the results of an empirical investigation of the factors that affect software safety based on an online survey with 99 practitioners from Chinese aviation organizations. The study proposes twenty potential factors covering five different categories (e.g., requirements, coding, testing, safety analysis, others). The survey focuses on the perspectives of the primary participants, managers, programmers, testers, consisting of a Likert scale evaluation of factors and questions about the participants' background. Many statistical analysis techniques, such as the relative weight method, correlation analysis, factor analysis and analysis of variance technique, are taken to analyze these factors. The findings are of great significance for further research and guidance on the development of safety-critical software. For practitioners, it provides estimates and quick guidance for software safety. The studies in this paper will be useful to the software safety community in aerospace industry as well as the wider software development community.

We demonstrate for the first time dual-channel all-optical AND logic operations based on intra-modal four-wave mixing (FWM) for on-off keying (OOK) signals in a multimode silicon waveguide. Correct temporal waveform sequences and clear eye-diagrams are presented to confirm the AND logic operations in this proof-of-concept work.

The main problem among the developing of the thickness mode piezoelectric air-coupled ultrasonic transducer is the acoustic impedance mismatch between piezoelectric plate and air. To solve this problem, a kind of porous composite material is introduced as the matching layer. The acoustic parameters measurement methods of the hollow glass microspheres filled epoxy resin composite material is studied in this article. On this basis, a pair of thickness mode air-coupled transducer with hollow glass microspheres filled epoxy resin as the matching layer is manufactured. A transmitting receiving testing system using this pair of transducers is built, the uplifting of receiving signal voltage peak-to-peak value is measured and compared with theoretical calculations.

Silicon optical modulators, one of the essential building blocks of silicon photonics technology, have made rapid progress in the last decade and start to show the competitive performances when comparing to traditional LiNbO 3 and III–V optical modulators.

We experimentally demonstrate a self-homodyne transmission system over 10-km few-mode fiber by transmitting pilot tone and signal in different modes simultaneously. A data rate of 156 Gb/s for 16-QAM and 234 Gb/s for 64-QAM self-homodyne detection few-mode fiber transmission system is experimentally demonstrated by transmitting pilot tone and data signal at individual modes. No frequency offset and phase noise compensation is required in the digital signal processing at the receiver side when optical delay line is used at the transmitter side. The study of effects of inter-modal crosstalk indicate that LP 01 and LP 11 modes are preferred to transmit pilot tone and signal, respectively.

Testing under the actual operational profile (OP) for high-reliability software can be expensive, time consuming or even infeasible in situations where performance of a system is dominated by infrequent but highly critical events. To solve this problem, testing using importance sampling was put forward for usage-based software reliability demonstration testing (SRDT). An extended research based on OP for software reliability growth testing (SRGT) is proposed. Firstly, the reinforced OP based on changing the probabilities of critical operations is suggested. Secondly, the principle of accelerated SRGT is proposed. Then an implementing framework is proposed. Finally, the accelerated method is applied on a software system. The experimental results indicate: compared with the growth testing approach based on original OP, the accelerated growth testing approach based on the reinforced OP can not only significantly decrease the required testing time and the required test cases, but also obtain the same testing conclusion and the unbiased estimation result.

The determination of software reliability indices is the primary task in the software reliability engineering. The indices are taken as not only the basis for the software reliability design and the constraints during the software development process, but also the foundation of the software's acceptance. Software reliability indices are usually divided into quantitative indices and qualitative indices. Quantitative indices are quantified software reliability parameters' values, such as software reliability is quantitatively defined as the probability of failure-free operation of a software program for a specified time under specified conditions. However, having a “number”, even with the appropriate accompanying evidence, is not generally sufficient to convince customers or even the system/software suppliers that the software satisfies its requirements. Thus, qualitative indices such as software reliability is also qualitatively defined as a set of attributes that bear on the capability of software to maintain its level of performance under stated conditions for a stated period of time. Attributes that relate to implementation of fault tolerance design, use of best engineering practices, application of specialized methods and techniques for ensuring reliability-critical requirements, and procedural methods to ensure mistake-proof loading and/or operation also provide evidence that improves the confidence that the software will not cause a system failure. So the qualitative indices can be regarded as the requirements for software reliability activities throughout the development process. Unfortunately, currently there is no systematic theory and approach for software reliability indices' determination. This paper proposes a method for determining the software reliability qualitative indices based on the two standards of SAE-JAI 003 and RTCA DO-I 78B which are widely used by the airworthiness and industrial sectors, as well as the best practices and management experiences of software reliability engineering. This paper proposes the method's principle, which determines the software reliability qualitative indices according to the profile formed by all stages of the software life cycle and the environment requirements, technique requirements, validation requirements and management requirements. Combined with the software's criticality levels, this paper also proposes a generic framework which recommends a variety of tailoring mechanisms and building guidelines to help users develop their demanded indices.

Numerical modeling for a sandwich dipole well logging transmitting transducer is conducted in this work. The characteristics for the first-order bending vibration of the sandwich transducer within different fluid loads are numerically analyzed. It is found that the resonant frequency and transmitting voltage response level are affected by the density, acoustic velocity and acoustic impedance of the fluid load. The numerical results were preliminarily validated by our experiment. The numerical analyses may provide useful suggestion for both the simulation design of logging transducer and the acoustic logging applications.

In the paper, a new and simple permanent magnet array is proposed and analyzed by using magnetic scalar potential. The characteristics of the synchronous permanent magnet planar motor (SPMPM) with new array such as linkage flux, back-EMF, and thrust are calculated by analytical method. The superiority and feasibility of the new magnet array are verified by comparing with Asakawa array, Chitayat array, and experiment data.

In order to reduce the influence on horizontal misalignment, which is caused by external velocity error under the external damping mode in Strapdown Inertial Navigation System (SINS for short), the technology of dual-system parallel processing is presented in the SINS calculation. Solution system 1 is the same as traditional solution model, in which log provides the external velocity; in solution system 2, external velocity is taken from solution system 1, and then the calculating in external damping mode continues after adjusting the damping parameters. Thus, the propagation path of external velocity error is changed, so that the influence on the accuracy of navigation information caused by this error is reduced. The simulation result shows that, the dual-system parallel processing technology can reduce the effect on horizontal misalignment effectively. And then, the experiment is operated by the FOG SINS which is made by our lab. The experiment results show the proposed method is valid.

The dynamics of epidemic spreading on time evolution network has attracted much attention. Here we present an alternate network, changing between scale free network and one-to-one random network, to simulate the topology structure between day and night. In our work, introducing the concept of effective contact, we investigate the epidemic spreading of SIR (susceptible-infected-recovered) model on the alternate network. Remarkably and quite excitingly, we find that spreading velocity is smaller on the alternate network than on scale free network. Numerical studies show that most of infected individuals do not keep disease state longer and will go to recovery state after a short time. We also study the recovery number as a function of the transmission rate and recovery probability.

The dynamics of epidemic spreading on adaptive networks has attracted great attention. Here we consider a generalized scenario, where the spatial distance is introduced into the study of adaptive networks. Meanwhile, the artificial self-avoid behavior for the susceptible individuals encountering with infectious individuals is optimized by the game strategies to mimic the public behavior more authentically. The distribution of spatial distance and the evolution of the disease prevalence have been investigated. We also report the comparison of the effects of spatial constraints on the network structure and the disease spreading process between the adaptive network and the non-adaptive network.

By means of analysis of software's usage, it can be known that the software's actual usage is just like a stochastic process, whose series of usage events are extended according to some probability distribution. If the statistical characteristics of software reliability test suite is that of the implementation in practice when customers actually use the software product, that is to say, the test process is converge to the actual usage process. Thus the minimal test effort can be determined by measuring the approximate extent of statistical characteristics of test suite to that of the whole input domain. Based on the sampling probability, one determination method of the minimal software reliability test effort is proposed in this paper and the recommended value is presented. Compared to one existing method, this method is based on the same principle of the test suite's statistical characteristics, but it adopts one different mathematical method whose demonstration detail is given and finally the influence factors of the minimal test effort are discussed in detail.

The routing protocol apply in WSN (Wireless sensor networks) is researched.WSN used in temperature monitoring system is designed, which is composed of three levels: the control center, the main network and the sensor sub-network, the network topology can be changed in accordance with environment needs. The routing path of WSN is multi-hop, the routing protocol that can choose the routing path adaptively. The WSN is deployed and running steadily, It proved that the routing protocol are reasonable.

It usually takes a long time or huge amount of test cases to do software reliability demonstration testing (SRDT) on a very high reliability software by conventional methods, which leads to the fact that the conventional SRDT methods cannot be put into use for accurately predicting failure rate of a very high reliability software. By means of importance sampling, for high reliability software systems, an accelerated SRDT method is put forward based on the strengthened operational profile (OP) which is constructed on Musa's operational profile. For discrete-type and continuous-type software, this paper describes the methods doing SRDT and estimating software reliability separately. An experiment is done to demonstrate the method and the results show that similar demonstration conclusion and reliability evaluation value were obtained with less test cases, i.e. the method meets the requirement of accelerating SRDT, which is valuable in demonstrating a very high reliability software in limited resources.

This paper analyzed the definition of software testability and its effect on software reliability test set. The conception of test effectiveness was proposed and the quantity model of minimal sample size in the software reliability demonstration testing (SRDT) introduced test effectiveness was put forward. Then the difference between the number of test cases with different test effectiveness was compared. It was demonstrated that the traditional method and the Bayesian method without prior knowledge were all the conditions where the test effectiveness equaled to zero and gave the most conservative value. Finally, the improved method combining with the test effectiveness was recommended. From the demonstration, the rationality of the method was suggested, which provided a new way to improve the efficiency of the SRDT method and ensure the higher reliability requirement.

The principle of finger vein recognition is researched, a device used to collect the finger vein images is produced. The images collected are eprocessed, the images are made to gray and combined filter is used to make the model more precision. In order to avoid the effect of area on and out of the finger profile, a method which implement by iterative threshold to extract the finger area and label the profile is used, the area which less than the given threshold is wiped off, the image height is normalized. Three recognition methods which based on moment character, wavelet moment and wavelet moment fusing with K-L and FDA transform rae researched and experimented.

The technology of laser scan range finder is researched, a line laser is used to survey the object section outlines. The system is composed of line laser, CCD camera, Frame Grabber, computer and the software. The mathematical model of the system is defined and studied, the error is analysed, the calibration method is resesrched. the system is calibrated and tested, the result showed that the survey data moved towards with the stripe shape tallies and the system achieve the accuracy requirements.

Wireless Sensor Network based on clustering robots are designed, clock synchronization principle of wireless network and typical time synchronigation algorithms are researched. The time synchronization algorithm based on send/receive proposed two-way synchronization mechanism and the flooding algorithm improve in combination with TPSN and FTSP algorithm; the key factors affecting the accuracy are analysis ;synchronization error between nodes are estimated ;the time synchronization errors for the whole network are estimated. The experimental results show the requirements of this clustering robots wireless network, time synchronization accuracy, scope and efficiency are meeted the cluster about the algorithm that are proposed in this paper in terms of time synchronization accuracy and energy consumption tradeoffs.

The correlative and uncertain relationship between software metrics and software reliability was analyzed. An approach for software reliability qualitative evaluation by using Bayesian networks was proposed. The rationale and process of this method were described in detail. The software reliability evaluation results were obtained by the causality reasoning. The proposed approach has been implemented in a case study. The experimental results constructed by the application process, key step and computational solution, showed that the approach was effective and could combine the expert experience, history data and various kinds of uncertain information to improve the modeling efficiency and validity, and provided a new method for software reliability evaluation.

In order to arrange the generators between hydrogenerators and themeturbine, the water data need to be sent to dispatch staffs timely. The daily submitted water data are intensive. And the dispatch staffs are pressured. Because the above objective conditions might lead to human error problems during the water submit processing, an artificial intelligence method of hydrological data validation and analysis based on neural network ensemble (NNE) is proposed. And a software based on this method are finished. It can improve the efficiency of dispatch staffs, and also can ensure the correct rate of water data submitted. The application results of daily water system data show the effectiveness and practicality of the method and the software.

Marketing science has matured to the point where it seems desirable to take stock of where we are, what we have learned, and develop a research agenda for extending the knowledge base that has developed. For some old topics, the need today is not for additional empirical data but for some means of making sense of the vast amounts of data that have been accumulated. Meta-analysis method can make quantitative generalizations across empirical studies on the related subject to achieve the above goal. By combing and comparing the existing studies, meta-analysis can give general conclusions to resolve controversy in previous research, improve the statistical power of research findings, point out research directions for future studies, and find out moderating factors for a specific relationship. To sum up, it is a superior method for knowledge accumulations of marketing or other behavior science in management filed. This article focuses on the application of meta-analysis in marketing field. It first claims the meaning of meta-analysis method for marketing research, then describes how to perform a meta-analysis in marketing field by using an example, and finally discusses the limitations of meta-analysis as a supplement.

Economic risk analysis of flood control engineering system is very important in risk management of flood disaster. The triangular fuzzy numbers theory was used to describe and deal with randomicity and fuzziness of economic risk system of flood control engineering, and the shortage and imprecision of datum information. In order to deal with the difficulties of operations of triangular fuzzy numbers and their functions, Monte-Carlo method was used to simulate triangular fuzzy numbers, which can transform the operations of triangular fuzzy numbers and their functions into the conventional operations of real numbers, and then a new economic Risk Analysis Method for flood control engineering system based on Stochastic Simulation of Triangular Fuzzy Numbers, named RAM-SSTFN for short, was established. The applied results of RAM-SSTFN show that economic benefit series of flood control engineering system can be simulated using Monte-Carlo method, that RAM-SSTFN can consider more complex things and give more exact computation results than the simple analysis methods of economic risk analysis of flood control engineering system, and that the common simple analysis methods should be used carefully in economic risk analysis of important regional flood control engineering system because their computation precision is not high. RAM-SSTFN can be used to deal with less, imprecise, random and fuzzy information, so it can be widely applied to risk management of different uncertainties systems.

A method for tracking on motion of small target is presented that is based on edge detection of image sequences. This approach detects the edge of small target of image sequences first and decides the position of centroid. According to the position tracking on motion of small target can be completed by least-square fit. The trajectory of tracking and collecting of small target is compared. The result implies that the tracking on small target comparing to experiment has little error and can achieve satisfactory effect.

Test coverage is a good indicator for testing completeness and effectiveness. This paper utilizes the logistic function to describe the test coverage growth behavior. Based on the logistic test coverage function, a model that relates test coverage to fault detection is presented and fitted to one actual data set. The experimental results show that, compared with three existing models, the evaluation performance of this new model is the best at least with the experimental data. Finally, the logistic test coverage function is applied to the NHPP software reliability modeling for further research.

This paper tries to assess the hazard of landslide of Wanzhou in Three Gorges Region by using GIS and information value method. Landslides have been located by interpretation of aerial photographs, topographic maps and field surveys, and the data collected and constructed into a spatial database with the help of GIS. Using factors including elevation, slope. gradient, slope aspect, lithology, distance to rivers, distance to roads, building distribution, and the distance to dividing line of Shaximiao Group and Suining Formation, a GIS-based assessment process is built. The model of information value is used to produce a map of slope instability. The results of the analysis were verified using the landslide location data. By the comparison between the result predicted and the actual distribution of landslide, we find the high consistency.

The radio fuze used in a strategic missile weapon system is a pulse radar altitude-meter. To avoid the difficulty in testing the radio fuze of a missile warhead, the paper introduces a new real-time test method. It uses a PC to simulate the echo data of target. Under the control of the PCI bus, the simulated echo data is passed to a high-speed DAC which can generate a video signal. The video signal is used to modulate the RF oscillator to generate an RF signal. With this technique, we can greatly simplify the testing procedure and shorten the testing time, compared with conventional techniques.