It is difficult to find Boolean functions used in stream ciphers that can meet all the necessary performance criteria. Recently, two classes of Boolean functions with many good cryptographic properties have been proposed by Tu and Deng based on correctness of a combinatorial conjecture about binary strings distribution (we call it Hamming constraint set). Tu-Deng conjecture has attracted much attention from cryptographers. In this paper we give a new method to obtain the explicit formulas for the cardinalities of some certain Hamming constraint sets, which partially proves Tu-Deng conjecture.

In this work we used some variable-selection techniques to find out the relevant factors that cause adolescent myopia, and established probabilistic models for myopia prediction. The research is based on a medical dataset consisting of two parts: medical measurement data of the youths and data on daily living habits obtained by questionnaire survey. We used some modern variable selection methods and the ROC curve to evaluate different modes. The results show that gender, axial length, corneal curvature, weekday sleeping time, distance vision without glasses, and remote adjustment reaction have important influences on adolescent myopia.

In the present study, in vitro method was used to assess human health risk of arsenic (As) in vegetables. Lettuce and rape were planted in the soil with different As pollutions, and bioaccessibility of As in the two vegetables was determined. Daily intake of As was also calculated, and the risk to human health was assessed. The results showed that the bioaccessibility of As decreased with the increasing concentration of As in the vegetables. Bioaccessibilities of As in the lettuce and rape were 29.13%-49.39% and 27.13%-51.95%, respectively, at solid-liquid ratio of 1:30. The values sharply rose to 42.39%-79.09% and 37.40%-76.59%, respectively, at solid-liquid ratio of 1:100. At the solid-liquid ratio of 1:30, the iron addition decreased the values to 22.24%-37.88% and 23.36%-47.56%, respectively, in the two vegetables, but the calcium addition made no change for the bioaccessibility of As. In raising the iron content of digestive juices by 0.0067 mol·L^-1, bioaccessibility of As could reduce by about 6.89%-11.51%. Iron can effectively reduce As intake.

As an important component of the global climate, Arctic sea ice is considered as an indicator of climate change. The study on the temporal change in the Arctic sea ice has the valuable theoretical importance for the global climate system as well as the practical significance in opening new shipping channels. In this study, we use 10 years' AMSR-E L2 products, which include the daily ice concentration of the Arctic sea, to calculate the monthly ice concentration, and then we analyze the change trajectories of ice concentration. The results show that the ice density in Arctic sea considerably decreased in these years. Generally, the Arctic ice cover reaches its peak in January and reaches its lowest record in September. Because of the rapid decline of sea ice, the ice between the Arctic and lands begins to vanish for few months in a year, which increases the likelihood of activities at Arctic sea, for example, opening up a new channel.

Agricultural modernization is a transition process from traditional agriculture to modarn agriculture, and the low-carbon agricultural way is an important approach in this transition. This study decomposes the CO₂ emission into five contributory factors based on an expanded Kaya identity. The five factors are general technology, agricultural low-carbon technology, rural affluence, indirect urbanization, and total population scale. With the incremental analysis we find that the rural affluence, urbanization, and total population scale are driving the agricultural CO₂ emission positively, while the general technology and agricultural low-carbon technology are driving the agricultural CO₂ emission negatively. Contribution without direction to total agricultural CO₂ emission caused by alteration of each factor is exhibited as: rural affluence influence > agricultural low-carbon technology influence > indrect urbanization influence > general technology influence > total population scale influence.

Taking Poyang lake ecological economic region as example, we establish a new-type urbanization evaluation index system to evaluate the new-type urbanization level and distribution of the counties in this region from 2004 to 2012, based on entropy method. Then we carry out spatial autocorrelation and build the spatial panel model to make econometric analysis. Results show that there is significant negative spatial autocorrelation in this region, which leads to the significant spatial polarization effect. This effect means that key areas or central cities developed at high speed and in proficient way for the new urbanization, mainly by absorbing capital investment, human resources, and knowledge in nearby regions. This effect has impact on the new urbanization process and the urbanization level of nearby regions. The gap between developed regions and developing regions will still exist in long run.

Larval and juvenile fish samples were collected from shoreline and shallow waters of the middle reaches of Lijiang River in May, June, and July of 2014. Four habitat types (A: compound bank with grait and aquatic plants, B: natural bank with sand and aquatic plants, C: constructed bank with grait and aquatic plants, and D: constructed bank and graits without aquatic plants) were investigated. We collected a total of 5416 individuals of 11 species, belonging to 3 genera, 5 families, and 10 orders. β-Cody diversity index measurement matrix demonstrated that types A and B and type D are significantly different in species richness level. One-way ANOVA and LSD analysis showed that the species richness and abundance of larval and juvenile fish were significantly higher in types A and B than type D, and were similar in types A and B. Aquatic vegetation had a significant impact on species richness and bank type combined with aquatic plant had a significant impact on larval and juvenile fish abundance. However, sediment had no significant impact on abundance. In a word, restoration of riparian and aquatic vegetation is crucial to the maintenance of species richness and abundance of larval and juvenile fish.

The deformation information of crust and upper mantle can be obtained from seismic anisotropy. SKS wave has good transverse resolution because of its almost vertical incidence. We collected a mass of seismic data in Yunnan region and calculated and analyzed the result of SKS wave splitting. Complex anisotropy and an obvious difference between south and north parts were found in this region. Then two-layer anisotropy model was used to analyze the data at KMI station, and a possible two-layer result which fits the observation data well was obtained. The splitting parameters are 130° and 0.2 s for the upper layer and 90° and 0.9 s for the lower layer.

This work investigated the parameter estimation problem for airborne interferometric synthetic aperture radar with rigid three-baseline. The considered system parameters are baseline orientation angle and interferometric phase offsets. So the least number of ground control points can be reduced to two. The effect of phase noise on the estimation accuracy is analyzed and a novel method called three-baseline union parameter estimation is proposed. The proposed method employed Newton optimal algorithm to solve the nonlinear estimation equations and used weighting process to deal with elevation accuracy difference of each baseline. Elevation difference between any two baselines is used to evaluate the efficiency of parameter estimation method. Simulation results indicate that the proposed method can obtain higher estimation accuracy than the conventional single baseline parameter estimation method.

In this work, SAR image compression algorithm based on compressed sensing is studied. Based on the theory of compressed sensing, a new approach for measurement matrix construction is proposed in dimension reduction domain while a new algorithm named improved iteratively reweighted least squares based on differential entropy for signal reconstruction is put forward as well. The conclusion can be drawn that the new compression algorithm is prior to traditional compression algorithms after the SAR image compression experiment and the compression performance comparison.

It is difficult to acquire optical remote sensing images with good quality in Wolong nature reserve because of the weather conditions. Meanwhile, the terrain is very complex and the species are very rich, which leads to poor classification results when using Landsat TM data to study the panda's habitat. In this work, an effective classification method is proposed to improve classification accuracy. First, three features including greenness, brightness, and wetness are extracted from Landsat TM image by tasseled cap transformation. Second, the abundance index is deduced by matched filtering method. Then, the rules for decision tree are established by combining the results of the tasseled cap and matched filtering methods, and used to map the land use classification distribution in the study area. Finally, the classification results are validated by field measurements. The results show that the greenness is an effective measurement for extracting forest, wetness can distinguish between meadow and shrub, and brightness can improve the classification accuracy for snow. A matched filtering method for spectral unmixing removes image noise and effectively detects the spectra of targets. The overall accuracy of the decision tree classifier reaches 83.33%, which is 7.67% higher than that of the maximum likelihood classifier. This method improves the effectiveness and accuracy of image classification in Wolong nature reserve for giant pandas.

A polarization loss of 3 dB is caused by circular polarized antenna when receiving the linear polarized signal in China area positioning system (CAPS). This work proposes to use dual-linear polarized antenna to receive CAPS signal and accordingly develops a signal acquisition and synthesis algorithm. The algorithm first performs signal acquisition with the dual-linear polarization antenna channels. According to the acquisition results the algorithm then synchronizes the signals. After the synchronization, it sums the signals from the two channels using the maximal-SNR (signal-to-noise ratio) combination. The algorithm is verified by its application to an experimental receiver. By analyzing the CAPS data acquired by the experimental receiver, it is found that the SNR of the synthesized signal increases by about 1.5 dB over the one-channel signals.

Android devices occupy 81.9% of the total smart phone market. However, the malicious applications of Android system are increasing, and the detection technology has become the hot topic in security research. We propose a new Android detection approach of privacy leakage malicious application based on directed information flow. This approach first decompiles the application and analyzes the permissions. Then, it builds directed information flow model according to the privacy points. By tracking the flows of the points, the information flows are monitored and the privacy leakages are detected. We tested 7 985 applications and detected 357 privacy leakage ones. We analyzed one of the results and confirmed that it was indeed a privacy leakge appliction. The results show that this new approach has good detection capacity.

Lightweight cipher has attracted much attention from the cipher community. Nowadays it is a trend to design lightweight cipher which performs well in both hardware and software. Although several theoretical and practical studies have been reported in the field of software implementation of lightweight cipher, it is still difficult to make a fair comparison of software implementation among different lightweight ciphers. In this paper we firstly present an approach of bitslice implementation of RECTANGLE, and then give its evaluation of software performance on X64 and X86 platforms. On 2.9 GHZ Intel(core) i5-4570s CPU, RECTANGLE achieves 34.2 cycles/byte for encryption and 30.9 cycles/byte for decryption for one block; on SSE instruction it achieves 5.2 cycles/byte for encryption and 5.1 cycles/byte for decryption; and on AVX instruction it achieves 2.6 cycles/byte for encryption and 2.5 cycles/byte for decryption.

We propose and develop a vulnerability exploitation scheme, called JoomHack. We use online shared and updatable vulnerability detection library of attack patterns, traverse them to exploit vulnerabilities, use attack patterns in database as seeds to generate new ones, and bring higher success rates. Experiments show that JoomHack takes advantage over Joomscan and other penetration tools of superiority when exploiting Joomla-based web system. JoomHack exploits vulnerabilities, assess risk for Joomla site effectively, and lay the foundation for web security work such as bug fixes. It is effective and has low cost for the improvement of web security.

Secured loan is an important form of business loans, but it may bring great risks. We construct a guarantee network based on guarantee relationships between enterprises, measure the basic attribute using the theory of complex network, and propose a risk propagation model based on SI model. Then the risk density in steady state and risk propagation velocity are defined to measure the anti-risk ability of networks. The experiment, based on the real data of some financial institution, shows that topology structures determine the anti-risk ability for network. Different risk infection sources would have different influences on risk propagation velocity and scope. This enlightens the bank on that the influences of a loan on the whole network should be also considered before granting of loans, in addition to the works of credit investigation for enterprise.

Observed data at 12 air-quality monitoring stations in urban Beijing in 2013 were analyzed for investigating the weekend effect of air pollutants and the reasons of weekend effect of O₃. Diurnal variation of SO₂ showed a single-peak curve with the peak at 11:00. Average hourly concentrations of SO₂ in weekends were higher than those on weekdays, with a daily average deviation of 15.57%. Diurnal variation of NO₂ showed a bimodal curve with the peaks at 08:00 and 22:00. Average hourly concentrations of NO₂ from 00:00 to 18:00 were higher in weekends than those on weekdays, with a daily average deviation of 7.50%. Diurnal variations of PM₁₀ and PM_2.5 showed bimodal curves on weekdays, while showed wave-shape curves in weekends. Average hourly concentrations of PM₁₀ and PM_2.5 in weekends were higher than those on weekdays with daily average deviations of 17.84% and 20.22%, respectively. Diurnal variation of O₃ in urban Beijing showed a single-peak curve with the peak at 16:00. Concentrations of O₃ from 11:00 to 24:00 were higher in weekends than those on weekdays, and concentrations of its precursors in weekends were higher than or close to those on weekdays. One possible reason was that the inhibition of NO on O₃ was weaker in weekends than that on weekdays in the O₃ suppression stage, which was favorable for the formation of O₃. The second reason was that concentration of CO in weekends was higher than that on weekdays, which promoted the formation of O₃ and led to weekend effect of O₃.