Analysis of Recent Secure Scan Test Techniques

Side channel attack may result in user key leakage as scan test techniques are applied for crypto-graphic chips. Many secure scan designs have been proposed to protect the user key. This paper meticulously selects three current scan test techniques, analyses their advantages and disadvantages and also compares them in security and area overhead. Users can choose one of them according to the requirements and further combination can be implemented to achieve better performance.

A review on the synergism between corrosion and fatigue of magnesium alloys:Mechanisms and processes on the micro-scale

Understanding the interaction between cyclic stresses and corrosion of magnesium(Mg)and its alloys is increasingly in demand due to the continuous expansion of structural applications of these materials.This review is dedicated to exploring the corrosion-fatigue mechanisms of these materials,with an emphasis on microscale processes,and the possibility of expanding current knowledge on this topic using scanning electrochemical techniques.The interaction between fatigue and corrosion of Mg alloys is analyzed by considering the microstructural aspects(grain size,precipitates,deformation twins),as well as the formation of pits.Furthermore,in the case of coated alloys,the role of coating defects in these phenomena is also described.In this context,the feasibility of using scanning electrochemical microscopy(SECM),scanning vibrating electrode technique(SVET),scanning ion-selective electrode technique(SIET),localized electrochemical impedance spectroscopy(LEIS)and scanning Kelvin probe(SKP)methods to study the corrosion-fatigue interaction of Mg alloys is examined.A comprehensive review of the current literature in this field is presented,and the opportunities and limitations of consolidating the use of these techniques to study the microscale processes involved in Mg corrosion-fatigue are discussed.

Study on Estimation Method of Rock Mass Discontinuity Shear Strength Based on Three-Dimensional Laser Scanning and Image Technique

The estimation of shear strength of rock mass discontinuity is always a focal, but difficult, problem in the field of geotechnical engineering. Considering the disadvantages and limitation of exist- ing estimation methods, a new approach based on the shadow area percentage （SAP） that can be used to quantify surface roughness is proposed in this article. Firstly, by the help of laser scanning technique, the three-dimensional model of the surface of rock discontinuity was established. Secondly, a light source was simulated, and there would be some shadows produced on the model surface. Thirdly, to obtain the value of SAP of each specimen, the shadow detection technique was introduced for use. Fourthly, compared with the result from direct shear testing and based on statistics, an empirical for- mula was found among SAP, normal stress, and shear strength. Data of Yujian （~ River were used as an example, and the following conclusions have been made. （1） In the case of equal normal stress, the peak shear stress is positively proportional to the SAP. （2） The formula for estimating was derived, and the predictions of peak-shear strength made with this equation well agreed with the experimental re- suits obtained in laboratory tests.

Experimental and numerical investigation of Weibullian behavior of grain crushing strength

The Weibullian behavior of single grain crushing strength was investigated experimentally and numerically with the aim of enhancing the understanding of rock grain breakage.The morphologies of pebble grains were obtained using white light 3D laser scanning and image processing.A grain shape library was constructed for grain shape analysis with different shape descriptors.The use of the shape library and grain stability analysis is discussed for a suggested procedure to rotate a grain to its most stable configuration.Single grain crushing tests were performed for 30 pebbles to obtain force-displacement curves and fracture patterns.Each grain was compressed diametrically between flat platens.As expected,the values of the stress at bulk fracture follow a Weibull distribution.A procedure for generating crushable agglomerates with realistic particle shapes was demonstrated,which was accomplished in the discrete element modeling(DEM)of the single grain crushing test.The work presented here is novel in that both the heterogeneous micro-structures and randomly distributed flaws are considered.The DEM results demonstrate that the proposed modeling approach and calibrated parameters are reliable and can reflect the crushing behavior of rock pebbles.Finally,three parametric studies were presented evaluating the effects of micro-crack density,micro-crack disorder,and grain morphology on the Weibullian behavior of the crushing strength,none of which has previously been thoroughly considered.These three studies provide a deeper insight into the origin of the Weibullian behavior of single grain crushing strength.

Effect of scratch on corrosion resistance of calcium phosphate conversion coated AZ80 magnesium alloy

In order to analyze the effect of scratch on the corrosion behaviour of a calcium phosphate conversion coating(CPCC)on AZ80,the electrochemical testing,scanning vibrating electrode technique(SVET),immersion test and hydrogen evolution experiment were performed to study the corrosion resistance of AZ80,AZ80 with CPCC and coated AZ80 with scratch.The results show that the coating improves the corrosion resistance of the AZ80 from a current density of(85±4)to(4±1)μA/cm^(2).When the coating was damaged,its protection on substrate would be reduced.The scratch with a length of around 12 mm on the coating reduced the corrosion resistance to a current density of(39±1)μA/cm^(2).In addition,the corrosion occurred initially in the scratch area and the corrosion site first occurred at the junction of the scratch and the coating.Besides,the micro corrosion mechanism of the specimen containing scratch was clarified.

Insight into microstructure evolution on anti-corrosion property of Al_(x)CoCrFeNiC_(0.01) high-entropy alloys using scanning vibration electrode technique

The effect of micro structure on the corrosion resistance of Al_(x)CoCrFeNiC_(0.01)(x=0.2,0.7,and 1.2)high-entropy alloys(HEAs) was systematically studied in this work.The microstructure evolution by regulating the Al content was analyzed in detail.Corrosion behavior was in situ monitored using the scanning vibration electrode technique,as well as some traditional electrochemical measurements.It is interesting to find that the compositions of body-centered cubic(bcc) and face-centered cubic(fcc)phases changed with the rising Al content,while the corresponding electrochemical responses for both phases were discriminated using the scanning Kelvin probe force microscopy method.Cr element was mainly distributed in the bcc phase for Al0.2(x=0.2) alloy,while its distribution changed to the fcc phase for the A10.7 and Al1.2alloys.The micro-galvanic corrosion cells formed between Cr-depleted and Cr-rich phases,resulting in the localized corrosion behaviors for the Al_(x)CoCrFeNiC_(0.01) HEAs,and the order for anti-corrosion property was Al0.2>Al1.2> Al0.7 HEAs.

A Rapid Calibration Technique for Scanning Line-Structured Laser Sensor

A novel procedure to calibrate the scanning line-structured laser sensor is presented. A drone composed of two orthogonal planes is designed, with the result that camera parameters and light-plane equation parameters is achieved simultaneously.

Loose Sand Particles Cemented by Chem/Bio-BaHPO_4 Powder

Bacillus subtilis was selected as the suitable microorganism,which could produce alkaline phosphatase and constantly hydrolyzed phosphate monoester in the mixture solution of bacteria with substrate,and then the PO4^3-was obtained.Bio-phosphate cement was prepared by alkaline earth element（Ba）ions reacting with PO4^3-in the mixture solution.Structure,size and thermal properties of the bio-phosphate cement were characterized by energy dispersive X-ray spectroscopy（EDS）,X-ray diffraction（XRD）,scanning electron microscopy（SEM）,and particle size analysis.The average crystallite sizes of chem-BaHPO4 and bio-BaHPO4corresponded to 11.99 and 24.13μm,respectively.Chem-BaHPO4 and bio-BaHPO4 were then adopted to bind loose sand particles.The results indicated that loose sand particles can be well cemented by the bio-BaHPO4powder into a bio-sandstone with a certain mechanical properties,and the average compressive strength of the bio-sandstones can be up to 0.83 MPa when the curing time was 14 d.Along with the method in future studies,there will be multiple new opportunities for engineering applications,for instance,the treatment of sandy soil foundation,remediation of heavy metals in contaminated soil,and so on.

Improvement of thickness uniformity and elements distribution homogeneity for multicomponent films prepared by coaxial scanning pulsed laser deposition technique

In conventional pulsed laser deposition （PLD） technique, plume deflection and composition distribution change with the laser incident direction and pulse energy, then causing uneven film thickness and composition distribution for a multicomponent film and eventually leading to low device quality and low rate of final products. We present a novel method based on PLD for depositing large CIGS films with uni- form thickness and stoichiometry. By oscillating a mirror placed coaxially with the incident laser beam, the laser＇s focus is scanned across the rotating target surface. This arrangement maintains a constant re- flectance and optical distance, ensuring that a consistent energy density is delivered to the target surface by each laser pulse. Scanning the laser spot across the target suppresses the formation of micro-columns, and thus the plume deflection effect that reduces film uniformity in conventional PLD technique is eliminated. This coaxial scanning PLD method is used to deposit a CIGS film, 500 nm thick, with thickness uniformity exceeding ±3% within a 5 cm diameter, and exhibiting a highly homogeneous elemental distribution.

Security of Computer Network and Measures of Defense

Along with the deepening of the reform and opening-up policy and the entering of the WTO,international exchange of economy and culture has become more and more frequent,Internet has become an indispensable part of our life,its rapid development brings great convenience to us,and all of the computers will be connected by Internet in the 21 century,thus the meaning of information security has changed substantially.It not only changes from a general guarding to a common defence,but from a specific field to a public subject as well.However,the opening and sharing of the Internet resource,unefficient supervision as well as various virus make people's information and belongings being in an extremely dangerous environment.The fight between hackers and anti-hackers,destruction and anti-destruction has already affected the stable running of the network and users' legal right,caused great economy damages and it could also threat our country's security.So a right understanding and in-time measures should be paid special attention to.The thesis firstly expatiates the current state of the network security and its importance,and discusses some major factors and threats that affect the network security.And the thesis also introduce some catalogues of the security techniques,some relevant information and their major characters,besides that,I enumerate some popular and effective methods of protecting our network,including the widely used firewall,and the meticulous techniques such as security scan techniques and techniques of intrusion detection.Lastly,some protective measures are stated.

Electro-optical sampling non-synchronous delay scanning measurement of electron beam bunch length at BFEL

The Electro-optical sampling delay scanning technique can be used for electron beam bunch length measurement. A novel non-synchronous delay scanning technique based on the electro-optical sampling measurements is presented. Based on Beijing Free Electron Laser （BFEL）, the electron beam bunch length was measured with the electro-optical sampling technique for the first time in China. The result shows that the electron beam bunch length at BFEL is about 5.6±1.2 ps.

σ-dominated charge transport in sub-nanometer molecular junctions

Quantum tunneling conductance of molecular junctions originates from the charge transport through theπ-orbitals(π-transport)and theσ-orbitals(σ-transport)of the molecules,but theσ-transport can not be observed due to the more rapid decay of the tunneling conductance in theσ-system compared to that in theπ-system.Here,we demonstrate that dominantσ-transport can be observed inπ-conjugated molecular junctions at the sub-nanometer scale using the scanning tunneling microscope break junction technique(STM-BJ).We have found that the conductance of meta-connected picolinic acid,which mainly occurs byσ-transport,is∼35 times higher than that of its para-isomer,which is entirely different from what is expected fromπ-transport through these systems.Flicker noise analysis reveals that the transport through the meta-connection exhibits more through-bond transport than the para-counterpart and density functional theory(DFT)shows that theσ-system provides the dominant transport path.These results reveal that theσ-electrons,rather than theπ-electrons,can dominate charge transport through conjugated molecular junctions at the sub-nanometer scale,and this provides a new avenue toward the future miniaturization of molecular devices and materials.

Application of Non-invasive Microsensing System to Simultaneously Measure Both H^＋ and O2 Fluxes Around the Pollen Tube

Various Ionic and molecular activities in the extraceUular environment are vital to plant cell physiological processes. A noninvasive microsensing system （NMS） based on either the scanning ion-selective electrode technique （SIET） or the scanning polarographlc electrode technique （SPET） is able to obtain information regarding the transportation of various Ions/molecules in Intact samples under normal physiological conditions. The two-probe simultaneous test system （2STS） Is an Integrated system composed of SIET, SPET, and a Xu-Kunkel sampling protocol. In the present study, 2STS was able to simultaneously measure fluxes of H^＋ and O2 of the Uly （Lillum Iongiflorum Thunb. cv. Ace） pollen tube while avoiding interference between the two probes. The results Indicate that the proton fluxes were effluxes, whereas the oxygen fluxes were Influxes, and they were closely correlated to each other surrounding the constitutive alkaline band region. Specifically, when the proton effluxes increased, the oxygen Influxes also increased. Therefore, the hypothesis of condensed active mitochondria existing in the alkalized area of the pollen tube proposed by Hepler＇s group is supported.

Relationship between La and Ce additions on microstructure and corrosion resistance of hot-dip galvanized steel

Scanning electron microscopy,X-ray diffraction,a neutral salt spray test,and electrochemical methods were applied to observe the microstructure and test the corrosion resistance of hot-dip galvanized steel before and after the addition of La and Ce.La/Ce mixture existed in the form of(La,Ce)Zn13 on the coated surface,decreased the coating thickness and accelerated the zinc dendritic growth.The corrosion current density of Zn-0.1La-0.1Ce coating was 63%less than that of pure Zn coating.This phenomenon can be explained that La/Ce mixture inhibited the transformation of Zn5(OH)8Cl2·H2O into Zn5(CO3)2(OH)6 or ZnO,reduced the time for appearance of red rust,and thus enhanced the stability of corrosion products and delayed the oxidation and corrosion processes of galvanized coating.La/Ce mixture improved the corrosion resistance compared to a single La or a single Ce addition.A competitive relationship between La and Ce was observed in the corrosion resistance improvement of hot-dip galvanized steel.

Galvanic Corrosion Behavior of Copper-Drawn Steel for Grounding Grids in the Acidic Red Soil Simulated Solution

The influence of pH and metallographic structure on the corrosion behavior of copper-drawn steel is studied with the simulated system.The effect of pH on the corrosion behavior of copper-drawn steel has been investigated using open-circuit potential,potentiodynamic polarization,galvanic current measurement,scanning electron microscopy and scanning vibrating electrode technique techniques.The steel is corroded as anode,while the corrosion of copper plate is protected as cathode.All the results revealed that pH and metallographic structure had a significant influence on the corrosion behavior of copper-drawn steel.With the decrease in pH value from 6 to 2.4,the corrosion rate of copper-drawn steel galvanic couple(Cu-Fe GC)obviously increased in the simulated solution of acidic red soil.The electric field formed by the Cu-Fe GC changes the direction of ion migration between the copper and drawn steel electrodes,which impacts the composition and microstructure of corrosion products formed on the electrode surface.

Localized Corrosion of Binary Mg-Ca Alloy in 0.9 wt%Sodium Chloride Solution

To further understand the localized corrosion of magnesium alloy, various in situ electrochemical techmques and ex situ electron microprobe analysis and SEM were used to monitor the corrosion process of Mg-l.0Ca alloy in 0.9 wt% sodium chloride solution. The results indicated that the localized corrosion was accompanied by the formation and thickening of a corrosion product film on the Mg-l.0Ca alloy. A localized corrosion of the alloy initiated selectively on the eutectic micro-constituent zones, then enhanced with the exposure, developed in depth with ring-shaped corrosion products accumulated around and finally formed a volcanic-like pitting. Based on the measurements, an electrochemical corrosion model was proposed accordingly to describe the formation mechanism of the volcanic-like pitting on the alloy in 0.9 wt% sodium chloride solution.

Initiation and propagation of localized corrosion induced by(Zr,Ti,Al)-O_(x) inclusions in low-alloy steels in marine environment

The effects of inclusions on localized corrosion of Zr–Ti deoxidized low-alloy steels in marine environment were investigated by various analytical techniques including scanning electron microscopy with X-ray microanalysis(SEM/EDS),confocal Raman microscopy(CRM),and in situ scanning vibrating electrode technique(SVET).It was found that complex(Zr,Ti,Al)-O_(x)inclusions were responsible for the initiation of localized corrosion.Localized corrosion pref-erentially occurred at Fe matrix adjacent to these inclusions and formed micro-gaps.In the early stage of corrosion,catalytic-occluded cells and the diffusion of chloride ions played a major role in the propagation of corrosion,further accelerating the dissolution of Fe matrix and(Zr,Ti,Al)-O_(x)inclusions.Combining SVET and CRM results,it revealed that the maximum anodic current density in local area gradually decreased with prolonged exposure time,indicating that corrosion products covered the steel surface and lowered the propagation rate of corrosion.In the later stage of corrosion,the barrier effect of corrosion products played an important role in inhibiting localized corrosion.

Effects of chloride on electrochemical and stress corrosion cracking behavior of 9Cr ferritic-martensitic steel

The electrochemical and stress corrosion cracking behavior of 9Cr ferritic-martensitic steel is investigated in the chloride environment by using the traditional electrochemical method, the scanning vibrating electrode technique and the slow strain rate test (SSRT). Results of the static corrosion tests and corrosion morphology show that the prior austenite grain boundaries and martensite lath boundaries are the preferred sites for pit nucleation and growth in chloride environment. Results of SSRT coupled with insitu electrochemical test show that the transition from pitting corrosion to uniform corrosion, as well as the nucleation of stress corrosion crack, is the synergistic effects of the chloride and applied load. Stress corrosion cracking of the steel in the chloride environment can be divided into three different regions as follows: fast and uniform corrosion activ-ity, microcrack nucleation and propagation, and active crack growth regions.

Inhibition of galvanic corrosion in Al/Cu coupling model by synergistic combination of 3-Amino-1,2,4-triazole-5-thiol and cerium chloride

Asynergistic inhibition study was carried out on an aluminium/copper galvanic coupling model in neutral aerated NaCl solution using scanning vibrating electrode technique(SVET).The approach allows the simulation of the local micro-galvanic cells of AA2024-T3 obtained from the potential difference between the intermetallic particles(IMPs)and the aluminium matrix.The inhibition effect of CeCl3 and 3-Amino-1,2,4-triazole-5-thiol(ATAT)was demonstrated by the reduction in the galvanic current density over Al and Cu surfaces.An improved inhibition from positive synergistic effect was revealed by the combination of the two inhibitors after 24 h of immersion,with the best inhibition recorded for Ce1.5ATAT3.5.Scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and time of flight secondary ion mass spectrometry(ToF-SIMS)were used to characterize the Ce-and ATAT-based complex film formed and to illustrate the mechanism of inhibition.