A top-down quasi triangular set algorithm and a triangular set algorithm for polynomial equations solution in finite fields are proposed and the complexity analysis for the first algorithm is given. Both of the algorithms are implemented in F3 and the experimental results show effectiveness of the algorithms.
Dynamic behaviors of thin plate under mechanical loads, magnetic field, and fluid influence were studied. Initially, governing equations of the plate in thermal and magnetic field were derived based on physical equation, non-linear geometric equation, and equilibrium equation. Differential dynamic system was established by applying Galerkin method. The numerical solution was obtained by using Runge-Kutta method and results induding time-history, phase trajectory, and Poincare map of the plate were given. The simulation revealed that magnetic field would inhibit the effect of nonlinear force in the dynamics system. The thermal field would influence on not only thermal deformation and stress of the thin plate, but also the dynamical behaviour characteristics of the system. The coupling effects of magnetic field and fluid play important roles on dynamics behaviours of the plate.
We propose a visible light coherent diffraction imaging method. The method employs a known standard object as a priori information in the object plane. Illuminating the tested sample and the coalition of the sample and the standard object, respectively, two diffraction patterns can be obtained to reconstruct the complex amplitude of the sample by the proposed iterative algorithm. We show the validity of the method via both numerical simulations and optical experiments. Since only two diffraction patterns are needed to achieve the lensless imaging, our method is simple to implement and has a high application potential.
We evaluate and analyze urban agriculture focusing on the relationship among its subsystems and the effect intensity. The results show that comprehensive evaluation index of urban agriculture increases steadily and keeps a positive tendency. Comparative advantages of both population and social subsystem are weakened since the loss of agricultural labor force and the urban-rural income gap, while the function of environment subsystem and resource subsystem is enhanced and promots urban agricultural mode transformation from the leading mode of economic subsystem to that of both environment and economic subsystems. With the increasing pressure of environment and resource, it is necessary for Beijing to build ecological urban agriculture system and get rid of the industrial way.
Taking Pan Yangtze River Delta (PYRD) as an example, this paper focuses on analyzing structural transformation and pattern evolution process of steel industry and the main influential factors. The results show that in PYRD the scale of steel industry has expanded rapidly and the product quality and industrial organization method have been improved constantly; and the industrial concentration degree has presented the trend of rise first and then drop but the concentration degrees of pig iron and crude steel are much higher than that of finished steel product. Jiangsu has become the province enjoying the highest concentration degree of steel industry, displacing Shanghai. Market demand, port location, technical level, enterprise strategy, and policy condition have become the major factors affecting the spatial layout of steel industry.
Geographical indication contains brand spillover effect and its promotion to rural economic development is increasingly apparent. This paper presents an empirical study on the spillover effect of Jiangsu geographical indication resources. The results show that at the province-level geographical indication has a positive role in promoting regional agricultural economy, but its promoting effect on farmers' income is not yet given; At the city-level geographical indication has positive impacts on agricultural economic development and farmers' income in Wuxi, Suzhou, Changzhou, and Yangzhou, but in other cities its brand spillover effect is not given due to a series of problems existing in protecting and developing geographical indication.
By applying the laws of the primary city,rank-size rule, and urban centrality,we analyzed the scale structure of the urban system in Sanjiang plain,and then analyzed the spatial structure including urban spatial distribution,urban spatial agglomeration, and spatial linkage. The results show that urban primacy ratio in Sanjiang plain is low,and Jixi has larger scale than Jiamusi,but less urban centrality. The dual-core structure has formed based on Jiamusi and Jixi cities,but the economy level of the central city is low and the economic linkage is weak. The spatial structure of urban system in Jiamusi is better than that in Jixi,but urban spatial agglomeration is less. Finally,we analyzed the problems of urban system in Sanjiang plain and some policy recommendations are presented.
Theoretically, one can calculate the information of steady-state geothermal gradient based on long-term temperature observations near the surface. We point out that it is difficult to determine heat flux in actual implementation by using meteorological records with a precision of 0.1 ℃. However, it may make a breakthrough by statistically analyzing a large amount of accumulated temperature observations. The influence of global warming on shallow geothermal gradient is also discussed. Although the monotonous increase in the ground temperature in a long term of centennial scale indeed leads to the decrease in shallow geothermal gradient and to the deviation from the geothermal gradient connected with heat flux, the calculated geothermal gradient errors are still within an acceptable range if the warming amplitude is within 1 ℃. Deriving geothermal flux based on meteorological data by a high-precision digital thermometer is feasible, but it requires us to accumulate data for a long term from now on.
Zhangfang area of Beijing is a typical example of the North China karst area, and the research on characteristics of joints and their impacts on karst and water enrichment is of great significance. In this paper, we attempt to study the characteristics of joints and discuss their influence on karstification with the method of probability and structural analysis. The earth's surface joint data that we use are got from geological surveys. Joints in this region have great influences on the karst development:1) the development extension of joints controls the extension and plane shape of karst development; 2) the oblique joints are favourable to the development of grikes and karst fracture zones while the intraformational joints are beneficial to the development of small and medium-sized interlayer karst caves; 3) the density of joints affects the degree of karst development; 4) joints filling with hard corrosion substance will restrain karst development while joints that filling with easy corrosion substance will be conducive to karst development; and 5) joints which formed early are more advantageous to the development of karst caves than the late joints.
Electrical conductivity method is a simple and rapid way to determine soil salinity, and it has been widely applied to modern soil, but limitedly applied to loess-paleosol sequence. In this paper, samples from Luochuan and Zhouyuan loess sections have been analyzed to measure the salinity by using electrical conductivity method. We focus on the impact of water-soil ratio and oscillation time on the determination, and the optimum conditions for conductivity determination of salinity in loess-paleosol sequence are identified on the basis of numerous experiments.
Considering the complex sand dune near-surface conditions in desert area,we carry out the forward simulation and data processing study. We present seismic wave numerical simulating algorithm and key parameters used for relief surface case. We introduce the random cave medium to depict the incompact sand dune structure,fill the practical air velocity above the surface,and simulate the seismic data acquisition in desert area. We take practical seismic data in desert area as example and use theoretical model to do the data processing and wave field analysis. The results show that the sand dunes' incompact structure in desert area is the main cause for the low S/N ratio in the pre-stack gather and stacking section. The pre-stack time migration method effectively improves the quality of the migration section and common reflection point gather by the weighted diffraction summation function,which provides certain significance for relief surface practical seismic data processing in desert area.
The security and reliability of data transmission are two essential and challenging subjects in wireless communication systems. A joint channel-security coding scheme provides both data secrecy and reliability in one single process to combat the interception and interference problems in an insecure and unreliable channel. In this paper, a bit-level secure error-correcting coding scheme, based on punctured Turbo codes which obtain an adaptive coding rate and encrypted coding stream, is presented. While decoding the Turbo coded frames, a novel windowed partial decoding iteration scheme, based on bit-level stopping criteria, is employed to prevent unnecessary iterations and reduce the decoding complexity. Simulations show that the encrypted coding stream can be well decoded by less complete iteration number and overall computation, compared with conventional methods.
As generally accepted in clinical psychology,mental health status can be expressed by behavior,including web behavior. Conventional mental health assessment is performed by self-report inventory, and it requires much manual efforts and cannot be done in real time. We aim to objectively predict user's mental health status,especially depression and anxiety. We confirmed the correlation between personality and mental health status in the conventional theory by examining a set of behavior data on sina microblog environment. Multi-task regression is proposed to predict online user's mental health status. The results indicate that mental health disorders are expressed by specific online behaviors and it is possible to predict user's degree of depression and anxiety through his/her microblog usage.
Considering the radio resource management problem in UMTS/WLAN heterogeneous networks,we propose a network selection and resource allocation algorithm with proportional rate constraint. In order to ensure the fairness among the users,the system sum-rate maximization problem subject to proportional rate constraint is considered. By relaxing the constraint and solving the problem,we get a deduction that the network selection is related to the user's rate ratio between different networks. Based on this,a low-complicity distribution algorithm is proposed. Simulation results show that the algorithm has minor degradation compared with the upper-bound performance. Additionally,the algorithm can effectively guarantee the fairness among users.
If an Android application could not protect its private components well in the process of inter-application communication, there would exist exposed component vulnerabilities. The current vulnerability mining technique cannot identify such vulnerabilities accurately. To solve this problem, we propose a new vulnerability mining method which combines Fuzzing with reverse analysis, and design a vulnerability mining tool named KMDroid. Experimental results show that KMDroid can discover the vulnerability of inter-application communication effectively.
Delivery of the application data in delay tolerant network relies on the custody transfer provided by the node storage. Fast release of the occupied node storage is significant for reducing congestion and enhancing network capacity. Studies have shown that the storage efficiency is affected by the size of packet at various network layers. We propose a storage management scheme based on cross-layer packet size optimization, OSUS. OSUS can dynamically adjust Bundle size and the transport layer frame size to maximize the node storage utilization. Simulation results show that, compared with traditional schemes where joint optimization algorithms are not adopted, OSUS can bring 15% improvement on average in the node storage utilization.
We provide a simple but general method to construct covariance functions of dependent Gaussian processes with multiple outputs. Our method relies only on existing covariance functions of Gaussian processes with single output. Several examples in computer experiments are given.
Two straight turbine blades with different internal structures and different cooling schemes have been studied using conjugate heat transfer method. We compare the performances of heat-pipe cooling and impingement cooling through analyzing the temperature on external surface,heat transfer coefficient of middle-span, and overall cooling effectiveness (OCE). The results show that the heat-pipe cooling leads to more uniform temperature distribution along the tailing edge of the blade and wider low-temperature region around the transition point. It has been found that the effectiveness of the heat-pipe cooling reaches to or even exceeds that of the impingement cooling under the same primary flow conditions.