线性移位寄存器在安全RSA模数中应用的研究

运用线性移位寄存器(LFSR)序列模2个不同素数时的周期一般不同这一性质,尝试构造分解另一类RSA模数的方法;指出对于RSA模数n=pq的一个素因子p,当p2+p+1,p3+p2+p+1,…其中之一仅含有小的素因子时,给出的算法能够分解合数n=pq,并给出了一个基于三级LFSR分解合数的实例来说明算法的具体运算步骤。根据该分解算法,在选取RSA模数时,为确保安全性,除避免已知的不安全因素以外,还需要保证n的素因子p满足p2+p+1,p3+p2+p+1,…均包含大的素因子。

Influence of pier height on the safety of trains running on high-speed railway bridges during earthquakes

Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is established.The reliability of the numerical model is verified by experiments.Then,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on bridges.The results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.

RSA推广循环攻击实效性与弱模问题的研究与分析

研究了一类RSA安全模数攻击方法的有效性,通过分析指出由于某些攻击方法成功概率可忽略,不能作为选择强安全RSA模数的理由,针对攻击方法的分析总结了当前安全RSA模数的含义,从实际安全角提高参数选择的效率。另外,对RSA模数2个素因子之差d=|p-q|不能太小的结果做了进一步研究,可以认为d为dl,m=ql-pm(l,m∈Z+)比较小时的一种特殊情况,由分析可以看出在选择RSA模数时需注意不要因特意选择比较大的d而忽略了2个素数关系的随机性,防止存在2者某种特殊的函数关系,提高安全性。

STUDY AND IMPROVEMENT OF MLS RELATIONAL DATA MODEL

The conception of multilevel security (MLS) is commonly used in the study of data model for secure database. But there are some limitations in the basic MLS model, such as inference channels. The availability and data integrity of the system are seriously constrained by it′s 'No Read Up, No Write Down' property in the basic MLS model. In order to eliminate the covert channels, the polyinstantiation and the cover story are used in the new data model. The read and write rules have been redefined for improving the agility and usability of the system based on the MLS model. All the methods in the improved data model make the system more secure, agile and usable.

Stability analysis of cohesive soil embankment slope based on discrete element method

In order to study the safety factor and instability process of cohesive soil slope, the discrete element method(DEM) was applied. DEM software PFC2 D was used to simulate the triaxial test to study the influence of the particle micro parameters on the macroscopic characteristics of cohesive soil and calibrate the micro parameters of DEM model on this basis. Embankment slope stability analysis was carried out by strength reduction and gravity increase method, it is shown that the safety factor obtained by strength reduction method is more conservative, and the arc-shaped feature of the sliding surface under the gravity increase method is more obvious. Throughout the progressive failure process, the failure trends, maximum displacements, and velocity changes obtained by the two methods were consistent. When slope was destroyed, the upper part was cracked, the middle part was sheared, and the lower part was destroyed by extrusion. The conclusions of this paper can be applied to the safety factor calculation of cohesive soil slopes and the analysis of the instability process.

The RSA Cryptoprocessor Hardware Implementation Based on Modified Montgomery Algorithm

RSA(Rivest-Shamir-Adleman)public-key cryptosystem is widely used in the information security area such as encryption and digital signature. Based on the modified Montgomery modular multiplication algorithm, a new architecture using CSA(carry save adder)was presented to implement modular multiplication. Compared with the popular modular multiplication algorithms using two CSA, the presented algorithm uses only one CSA, so it can improve the time efficiency of RSA cryptoprocessor and save about half of hardware resources for modular multiplication. With the increase of encryption data size n, the clock cycles for the encryption procedure reduce in (T(n^2),) compared with the modular multiplication algorithms using two CSA.

Numerical simulation of protection range in exploiting the upper protective layer with a bow pseudo-incline technique

The developing processes of stress and deformation fields of a protected layer after mining an upper-protective layer with a bow pseudo-incline technique were simulated to locate the protection region. The pressure relief of the protected layer was analyzed after mining the upper-protective layer. The pressure relief angle along the strike and incline were located according to the roles of protection of the deformation and stress pressure-relief of the protective layer after mining. This results show that the upper-protective layer with the bow pseudo-incline technique have an upper and downside pressure relief angle of 85 and 68 degrees respectively; the distribution of strike pressure relief angles along the pseudo-incline working face is uneven and their values range from 38.3 to 51 degrees. The pressure relief angle of the inclined middle location was the largest. The distribution of the protection region of the upper-protective layer with the bow pseudo-incline teelmique located by practical tests and numerical simulation is essentially consistent, compared with the results obtained by these methods.

Construction of reasonable pillar group for undersea mining in metal mine

In order to achieve the safe mining in Sanshandao Gold Mine,five schemes of secure pillar group are designed.Using the method of the renormalization group,the failure mechanism of the pillar group is explored,and the safety factor of the pillar system is also obtained.The displacement characteristics,stress-strain laws,distribution of plastic zone and damage range of different pillar group are analyzed using numerical calculation software FLAC3D.To determine a reasonable pillar group scheme,the pillar stability and roof deformation are utilized to evaluate the safety of the pillar group.In addition,the theory of fuzzy comprehensive evaluation is adopted to verify the optimal scheme.The pillar group with the lowest roof deformation value is chosen as the optimal plan,which renders a factor of safety of 2.06 for the pillar group.According to this scheme,pillars with the width of 10 m are set along the strike of undersea deposit with the interval of 50 m.Rib pillars of 15 m in width are set at the location of the exploration line of 127,151 and 167.The analysis can be used to provide guidance for optimal design of pillar structures in undersea mining.

Numerical simulation and actual research on safety and suitable position of roadway driving along next goaf

In view of the stress concentration problem left by the joint coal seams mining since the reservation of the coal pillar, it was proposed that non-pillar mining technology be used in Dongrong No.2 coal mine. The numerical simulation software FLAG2D was used to draw the relationship between surrounding rock deformation of roadway driving along next goaf and the size of the coal pillar, so the safety and suitable position of roadway was determined. The distribution of lateral abutment pressure was measured by using the ZYJ-30 drilling stress gauge in the coal wall. The conclusions of the numerical simulation were verified.

Numerical simulation of dewatering thick unconsolidated aquifers for safety of underground coal mining

With an increase of mining the upper limits under unconsolidated aquifers, dewatering of the bottom aquifer of the Quaternary system has become a major method to avoid water and sand inrushes.In the 8th District of the Taiping Coal Mine in south-western Shandong province, the bottom aquifer of the Quaternary system is moderate to excellent in water-yielding capacity.The base rock above the coal seam is very thin in the concealed coal field of the Carboniferous and Permian systems.Therefore, a comprehensive dewatering plan from both the ground surface and the panel was proposed to lower the groundwater level in order to ensure mining safety.According to the hydrogeologic conditions of the 8th District, we established a numerical model so that we could simulate the groundwater flow in the dewatering process.We obtained the simulation parameters from previous data using backward modeling, such as the average coefficient of permeability of 12 m/d and the elastic storage coefficient of 0.002.From the same model, we predicted the movement of groundwater and water level variables and obtained the visible effect of the dewatering project.Despite the overburden failure during mining, no water and/or sand inrush occurred because the groundwater level in the bottom aquifer was lowered to a safe water level.

Prediction and safety analysis of additional vertical stress within a shaft wall in an extra-thick alluvium

An alluvium with a sandy aquifer at the bottom,but lacking an effective impermeable layer between the sandy aquifer and bedrock is referred to as a special alluvial stratum.Impacted by the drainage of the aquifer due to mining activities,a shaft wall in this special alluvial stratum will be subject to a downward load by an additional vertical force which must be taken into consideration in the design of the shaft wall.The complexity of interaction between shaft wall and the surrounding walls makes it extremely difficult to determine this additional vertical force.For a particular shaft wall in an extra-thick alluvium and assuming that the friction coefficient between shaft wall and stratum does not change with depth,an analysis of a numerical simulation of the stress within the shaft wall has been carried out.Growth and size of the additional vertical stress have been obtained,based on specific values of the friction coefficient,the modulus of elasticity of the drainage layer and the thickness of the drainage layer.Subsequently, the safety of shaft walls with different structural types was studied and a more suitable structural design,providing an important basis for the design of shaft walls,is promoted.

Design of intrinsically safe power supply

Aiming to make a high power direct current supply safely used in coal mine production, this paper made a deep research on characteristics of intrinsically safe power supply, using the mathematical model established according to coal mine intrinsic safety standards. It provides theory support for the application of high power intrinsically safe power supply. The released energy of output short circuit of switch power supply, and the close related factors that influence the biggest output short-circuit spark discharge energy are the theoretical basis of the power supply. It is shown how to make a high power intrinsically safe power supply using the calculated values in the mathematical model, and take values from intrinsically safe requirements parameters scope, then this theoretical calculation value can be developed as the ultimate basis for research of the power supply. It gets the identification method of intrinsically safe from mathematics model of intrinsically safe power supply characteristics study, which solves the problem of theory and application of designing different power intrinsically safe power supply, and designs a kind of high power intrinsically safe power supply through this method. energy, flyback

Study of coal and gas outbursts by numerical modeling approach

Abstract During mining or road-way development, the distribution of stress and coal pore pressure in the coal face and rib around the new opening will change, under certain conditions, dynamic failure of coal in the form of an outburst can occur. In the modeling studies presented in this paper, an outburst was considered to consist of three distinct stages： preinitiation, initiation and post-initiation, which takes into account the major processes and mechanisms that can influence both outburst-proneness and post-initiation outburst behavior. The model has been applied to simulate the effects of mechanisms in the coal matrix, coal strength, coal damage, geological structures on outbursts. The model constructed using the FLAC software, which were undertaken to research the effects on outbursts of coal strength pressure gradient, and other factors.

Interaction analyses between tunnel and landslide in mountain area

This paper focuses on the analytical derivation and the numerical simulation analyses to predict the interaction influences between a landslide and a new tunnel in mountain areas. Based on the slip-line theory, the disturbance range induced by tunneling and the minimum safe distance between the tunnel vault and the sliding belt are obtained in consideration of the mechanical analyses of relaxed rocks over the tunnel opening. The influence factors for the minimum safe crossing distance are conducted,including the tunnel radius, the friction angle of surrounding rocks, the inclination angle of sliding belt,and the friction coefficient of surrounding rocks. Secondly, taking account of the compressive zone and relaxed rocks caused by tunneling, the Sarma method is employed to calculate the safety factor of landslide. Finally, the analytical solutions for interaction between the tunnel and the landslide are compared with a series of numerical simulations, considering the cases for different perpendicular distances between the tunnel vault and the sliding belt. Resultsshow that the distance between the tunnel vault and the slip zone has significant influence on the rock stress and strain. For the case of the minimum crossing distance, a plastic zone in the landslide traversed by tunneling would be formed with rather large range, which seriously threatens the stability of landslide. This work demonstrates that the minimum safe crossing distance obtained from numerical simulation is in a good agreement with that calculated by the proposed analytical solutions.

Multidisciplinary design optimization on production scale of underground metal mine

In order to ensure overall optimization of the underground metal mine production scale, multidisciplinary design optimization model of production scale which covers the subsystem objective function of income of production, safety and environmental impact in the underground metal mine was established by using multidisciplinary design optimization method. The coupling effects from various disciplines were fully considered, and adaptive mutative scale chaos immunization optimization algorithm was adopted to solve multidisciplinary design optimization model of underground metal mine production scale. Practical results show that multidisciplinary design optimization on production scale of an underground lead and zinc mine reflect the actual operating conditions more realistically, the production scale is about 1.25 Mt/a (Lead and zinc metal content of 160 000 t/a), the economic life is approximately 14 a, corresponding coefficient of production profits can be increased to 15.13%, safety factor can be increased to 5.4% and environmental impact coefficient can be reduced by 9.52%.

Design Method of Rigid Blast Wall Under the Explosion of Vehicular Bomb

Blast wall can prevent vehicles from approaching the protective building and can reduce the destructive power of shock wave to a certain extent.However,majority of studies on blast walls have some shortcomings.The explosion test data are few.Most exsiting studies focus on the propagation of shock wave and the influence of blast wall on the propagation of shock wave.Discussion on the main parameters of blast wall design is meagre,such as the design of safety distance,the distance from the blast wall to the protective building,height and width of the blast wall.This paper uses the finite element programme LS-DYNA to design the blast wall.To analyze the convergence of the finite element model and to determine the mesh size of the model,this paper establishes several finite element models with different sizes of meshes to verify the model.Then,the overpressure distribution of the shock wave on the protective building is simulated to implement the blast wall design.The geometric parameters of the blast wall are preliminarily determined.And the influence of the safety distance on the overpressure of the building surface is mainly discussed,so as to determine the final design parameters.When the overpressure is less than 2 kPa,it is considered that there will be no damage to people caused by flying fragments.Eventually,the blast wall height is 3 m,the thickness is 1 m,and the safety distance is 35 m.The proposed method is used to demonstrate the design method,and the final design parameters of the blast wall can thus be used for reference.

Research on stateful public key based secure data aggregation model for wireless sensor networks

Data aggregation technology reduces traffic overhead of wireless sensor network and extends effective working time of the network,yet continued operation of wireless sensor networks increases the probability of aggregation nodes being captured and probability of aggregated data being tampered.Thus it will seriously affect the security performance of the network. For network security issues,a stateful public key based SDAM( secure data aggregation model) is proposed for wireless sensor networks( WSNs),which employs a new stateful public key encryption to provide efficient end-to-end security. Moreover,the security aggregation model will not impose any bound on the aggregation function property,so as to realize the low cost and high security level at the same time.

The Cloud Storage Ciphertext Retrieval Scheme Based on ORAM

Due to its characteristics distribution and virtualization, cloud storage also brings new security problems. User＇s data is stored in the cloud, which separated the ownership from management. How to ensure the security of cloud data, how to increase data availability and how to improve user privacy perception are the key issues of cloud storage research, especially when the cloud service provider is not completely trusted. In this paper, a cloud storage ciphertext retrieval scheme based on AES and homomorphic encryption is presented. This ciphertext retrieval scheme will not only conceal the user retrieval information, but also prevent the cloud from obtaining user access pattern such as read-write mode, and access frequency, thereby ensuring the safety of the ciphertext retrieval and user privacy. The results of simulation analysis show that the performance of this ciphertext retrieval scheme requires less overhead than other schemes on the same security level.

Analytical Model and Algorithm of Fuzzy Fault Tree

In the past, the probabilities of basic events were described as triangular or trapezoidal fuzzy number that cannot characterize the common distribution of the primary events in engineering, and the fault tree analyzed by fuzzy set theory did not include repeated basic events. This paper presents a new method to analyze the fault tree by using normal fuzzy number to describe the fuzzy probability of each basic event which is more suitably used to analyze the reliability in safety systems, and then the formulae of computing the fuzzy probability of the top event of the fault tree which includes repeated events are derived. Finally, an example is given.

Numerical simulation of scattering wave imaging in a goaf

Goafs are threats to safe mining.Their imaging effects or those of other complex geological bodies are often poor in conventional reflected wave images.Hence,accurate detection of goafs has become an important problem,to be solved with a sense of urgency.Based on scattering theory,we used an equivalent offset method to extract Common Scattering Point gathers,in order to analyze different scattering wave characteristics between Common Scattering Point and Common Mid Point gathers and to compare stack and migration imaging effects.Our research results show that the scattering wave imaging method is more efficient than the conventional imaging method and is therefore a more effective imaging method for detecting goafs and other complex geological bodies.It has important implications for safe mining procedures and infrastructures.