Hydrophobic AP/CBC nanostructured materials were prepared by the solution dipersion-freeze drying method with ammonium perchlo-rate(AP) and carbonized bacterial cellulose(CBC) as raw materials, using polymethylhydrosiloxane (PMHS),dodecafluoroheptylpropyltrimetho-xysilane (FAS) and methyltriethoxysilane (MTES) as modifying agents.The morphology, structure and moisture absorption properties of AP/CBC nanostructured materials were characterized by field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectrometer (FT-IR),X-ray diffractometer (XRD), contact angle tester, constant temperature and humidity box, laser particle size analyzer, contact angle tester and so on.The results show that compared with pure AP, the morphology change of nano-structure materials is larger, and AP is uniformly distributed in the hole of the three-dimensional net-work.Moreover, the surface of the modified nanostructured material after being modified is uniformly coated with modifier, which helps to form a hydrophobic surface.The contact angels of the AP/CBC nanostructured materials modified by PMHS, FAS,MTES are (109±2)°, (56±2)°, (55±2)°, respectively, which are greatly improved compared with pure AP.The modified AP/CBC nanostructured materials have lower moisture absorption than the pure AP, especially the AP/CBC nanostructured materials modified by PMHS have the lowest moisture absorption of 0.31%.

In order to precisely measure the ion parameters in a microwave electron cyclotron resonance plasma using an ion sensitive probe, the dependences of the current-voltage (I-V) characteristics on the shielding height (h) and the potential difference between inner and outer electrodes (V-B) have been investigated at different working pressures of 0.03 Pa and 0.8 Pa. Results show that the I-V curves at higher pressure are more sensitive to the variation of h than those at lower pressure. The influence of V-B on ion temperature (T-i) measurement becomes more prominent when the pressure is increased from 0.03 Pa to 0.8 Pa. Under both pressures, the optimized h is obtained at the condition where the current reaches zero in the positive voltage region with a suitable V-B of -1.5 V because of effective shielding of the electron ExB drift.

Power analysis attacks explore the encrypted information by monitoring the power traces of physical crypto-systems. Among all published power analysis attacks, correlation power analysis (CPA) is the most effective attack that has been reviewed by many researchers recently. Meanwhile, various countermeasures have been proposed to against CPA attacks. In this work, a novel approach based on stochastic logics is proposed to enhance the resistance against CPA attacks. The probabilistic bitstreams, generated by encoders with random numbers, are used to represent binary logic states. The output bitstreams are converted back into the binary logics using decoders, ensuring the capability with other conventional logic functions. An 8-bit AES SBox has been implemented using the proposed structure in VHDL and verified in ModelSim. Experimental result shows that three factors affect the accuracy of stochastic logic devices: the length of bitstreams for a given logic state, the decision weight of the encoders, and the repeat times of an input. A specified side-channel attack (SCA) standard evaluation FPGA board (SASEBO-GII) has been used for power measurement. Experimental results also demonstrate that the proposed design could effectively randomize the power consumption so that CPA attacks are not able to reveal the correct secret key.

Etching with oxygen ions produced by ECR plasma with an asymmetric magnetic mirror field was investigated as a potential technique for polishing CVD diamond. The morphology, structure and roughness of the diamond film surface before and after etching were analyzed respectively using scanning electron microscope (SEM), Raman spectroscopy and surface roughness measuring instrument. It was found that the ridges on diamond surface had been preferentially etched away and thereby the surface roughness decreased from 3.061 to 1.083 pin after 4 h etching. Meanwhile, non-diamond phase appeared on surface and dramatically increased with the extending of etching time. In order to fundamentally understand the etching mechanism, an etching model of diamond film was reasonably proposed on the ground of the experimental results and the theory of plasma physics. The as-generated ions taking screw movement are firstly accelerated along the magnetic field lines in the plasma and collisional presheath, and then deflected from their route towards the diamond film in the MP. When coming into Debye sheath, the motion of ions will be deflected further and strongly accelerated by electric field in the direction normal to the (1 1 1) crystal facets. This process gave rise to energetic ion bombardment towards every (1 1 1) crystal face, and thereby caused preferential etching of pyramidal crystallites. (C) 2013 Elsevier B.V. All rights reserved.

A highly-efficient magnetoelectric heating not only improves ion temperature of electron cyclotron resonance (ECR) plasma, but also reforms the radial and axial distribution of ions, thereby promoting the application of ECR plasma to the etching of chemical vapor deposition diamond films. In this paper, a ring-electrode is replaced by a cylinder-electrode, and the effects of cylinder-electrode on the ion temperature and density are studied. The ion heating effects in the cases of cylinder-electrode and ring-electrode are compared. The results indicate that cylinder-electrode can produce higher ion temperature than ring-electrode at the same anode voltage. Ion temperature at each radial point changes a lot when the cylinder-electrode is used to heat ions. The ion temperature inside cylinder-electrode has a big radial variation while it has a good radial uniformity at downstream of cylinder-electrode. The effect of magnetoelectric heating on ion density is small. Using cylinder-electrode to heat ion is beneficial to the transport and axial uniformity of ions.

Magnetoelectric heating was used to heat ions in an ECR plasma with a magnetic mirror field.The temperature and density of ions were measured by an ion sensitive probe(ISP) before and after magnetoelectric heating in order to investigate the influence of the anode ring’s radius,axial position and working pressure on magnetoelectric heating.Results showed that a suitable radius of the anode ring could improve the ion temperature effectively and the optimal size of the anode ring depended on the cyclotron radius of ions.The radial uniformity of the ion density was improved by increasing the radius of the anode ring after heating.The magnetic mirror field could reduce the loss of ions caused by collision with the wall of the chamber and it was beneficial to increase the ion temperature and the ion density.It was suitable to heat the ions when the anode ring was set at the center of the magnetic mirror field where there was a weaker magnetic field strength.Lower pressure contributed to the increase in the ion temperature and efficiency of magnetoelectric heating.

Nitrogen-doped and undoped diamond films grown by microwave plasma chemical vapor deposition (CVD) were etched by electron cyclotron resonance (ECR) plasma with asymmetric magnetic mirror field. The influences of nitrogen doping on the etching characteristic of CVD diamond films are studied by scanning electron microscope (SEM), X-ray photoelectron spectroscopy(XPS), and surface roughness measuring instrument; and the etching mechanism is explicated in detail by etching models. It is found that the crystal edges are dramatically etched for the nitrogen-doped diamond film, while the (111) facets are etched and crystalline grains collapse for the undoped diamond film. And after etching by ECR plasma for 4 h, the nitrogen-doped diamond film surface roughness decreases from 4.761 μm to 3.701 μm, while the surface roughness of the undoped film decreases from 3.061 μm to 1.083 μm. The results indicate that nitrogen doping has great influence on the etching characteristic of the CVD diamond films. Nitrogen-doping deteriorates the film quality and increases the defect density in the crystallites. And the defects distributed in the crystal edge lead to dramatically etching of the crystal edge. Compared with the nitrogen-doped diamond film, the defect density in undoped diamond film is relatively low and the distribution of defects is comparatively uniform, resulting in the fact that (111) facets would suffer from oxygen cyclotron ion beams bombardment and so grains of the film collapse. The reason why the surface roughness of nitrogen-doped diamond film decreases less than the undoped diamond film is that the movement of ions is affected by the electrons emitting from crystal edge, which weakens the ion bombardment on (111) facets.

With the massive deployment of mobile devices and sensor networks, resistance against side-channel attacks in cryptographic systems has become an active research topic in recent years. While various security measures exist in literature, most of them are deterministic in nature, where the same input plaintext always results in the same power trace with a given key. Thus, attackers can still aggregate the small deviations between the power traces to identify the correct key. Towards this, random dynamic voltage scaling has been proposed in the literature, which is demonstrated to be effective against Differential Power Analysis (DPA). In this paper, we evaluate this approach, along with the expanded feature of spatial randomness, to resist Correlation Power Analysis (CPA).

The recently proposed asynchronous nanowire crossbar architecture is envisioned to enhance the manufacturability and robustness of nanowire crossbar-based configurable digital circuits by removing various timing-related failure modes. Even though the proposed clock-free nanowire crossbar architecture has numerous technical merits over its clocked counterparts, it is still subject to high defect rates inherently induced by the nondeterministic nanoscale assembly of nanowire crossbars. To address this issue, a novel post-configuration repair strategy specific to the asynchronous nanowire crossbar architecture has been proposed. The proposed repair strategy is to selectively test highly defect-prone ON-state programmed crosspoints and reconfigure the given logic function to circumvent the ON-crosspoints tested as faulty by utilizing redundant rows/columns.

In this work, a novel design and optimization method for programmable gate macro blocks (PGMB) in the newly proposed Asynchronous Nanowire Reconfigurable Crossbar Architecture (ANRCA) is presented. ANRCA is based on a self-timed logic referred to as the Null Convention Logic (NCL). Since there is no global clocking and clock distribution network, all failure modes related to timing will be either eliminated or relaxed. The proposed architecture is anticipated to have higher manufacturability and robustness that are critical factors in nanoscale systems due to nondeterministic nature of nanoassembly. In order to facilitate efficient programming and flexible reconfiguration, a new hierarchical reconfigurable architecture for ANRCA is also proposed. Various configurable logic block structures have been considered and also their programming and reconfiguration issues are discussed.

实践教学是核工程与核技术专业人才培养中非常重要的环节。华北电力大学核科学与工程学院秉承了华北电力大学厚基础、重实践的教学思想,高度重视实践教学,狠抓实验实践环节和过程的教学设计和实验室建设,形成了一套具有华北电力大学特色的核工程与核技术专业实践教学体系,为培养具有基本技能、工程应用及创新思维的高素质复合型核工程应用人才提供理论和实践基础。

利用非对称磁镜场电子回旋共振等离子体产生的氧回旋离子束刻蚀了化学气相沉积金刚石膜,研究了工作气压和磁电加热电压对金刚石样品附近的离子温度和密度的影响,并分析了金刚石膜的刻蚀和机械抛光效果.结果表明:当工作气压为0.03 Pa,磁电加热电压为200 V时,离子温度和密度最大,分别为7.38 eV和23.8×1010cm-3.在此优化条件下刻蚀金刚石膜4h后,其表面粗糙度由刻蚀前的3.525μm降为2.512 μm,机械抛光15 min后,表面粗糙度降低为0.517 μm,即金刚石膜经离子束刻蚀后可显著提高机械抛光效率.

This paper demonstrates a recently proposed low-power side channel attack (SCA) resistant asynchronous S-Box design for the AES crypto-systems. A specified side channel attack standard evaluation FPGA board (SASEBO-GII) is used to implement the design. This board includes two Xilinx FPGAs to perform the cryptographic function and the configuration function separately. This prevents the power trace of the configuration circuit from interfering with the power trace of the cryptographic circuit, so that the measurements of making/resisting power analysis attack can be done fairly. The proposed design is clock free and has flatter power peaks since it is based on a delay-insensitive logic paradigm referred to as null convention logic (NCL). Comparisons between the existing synchronous S-Box design and the proposed asynchronous design are performed in the various aspects; speed, area, total power consumption, and results of differential power analysis (DPA) attack, one of the most powerful cryptanalysis that could extract the secret keys of cryptographic devices. Experimental results shows that the proposed asynchronous S-Box is resistant to DPA attacks and has a lower power consumption than its synchronous counterpart.

The demand for enhanced security in cryptographic systems is increasing rapidly in recent years with the development of mobile devices, such as smart phones and tablets. One of the most popular cryptographic devices that are used in these security sensitive devices is the smart card, which provides the security identification and authentication for those applications. To secure these cryptographic devices from various attacks has grown to become an attractive research topics. While recent advancements in public-key cryptographic algorithms try to eliminate or reduce the theoretical weaknesses to resist attacks, an alternative way to obtain the information of secret keys is from the physical implementation of the crypto-hardware. In this work, a random dynamic voltage scaling (RDVS) design has been proposed and implemented into an AES S-Box which is designed using asynchronous delay-insensitive logic referred to as Null convention logic (NCL). NCL utilizes symbolic completeness of expression to achieve self-timed behavior. It has been demonstrated that NCL contains all the properties to resist common forms of side-channel attack (SCA). RDVS is designed to enhance the resistance against SCA in the way of randomly changing the supply voltage so that “random noise” can be injected into the power traces to make the SCA more difficult to attack.

The magnetoelectric heating is investigated on an ECR plasma device. The ion temperatures are measured by ion sensitive probe (ISP) before and after magnetoelectric heating. The influences of bias voltage of electrical ring, magnet field and pressure on ion temperature and the efficiency of ion heating are studied. The results indicate that the whole heating of the plasma is accomplished through the magnetoelectric heating of the ions in the sheath of the electric ring and the radial transport of the heated ions. The ion temperature in the axial area increases with the bias voltage of electric ring, and their relationship is nonlinear. The ion temperature increases more than 20 eV when the bias voltage is 1000 V. A heating efficiency is achieved to be as high as 2%2.5% and increases with the bias voltage increasing. The magnetic field strength plays an important role in the limitation and heating of the ions. The efficiency of the magnetoelectric heating increases with the increase of the magnetic field strength when the magnetic field strength changes from 6.310-2T to 8.710-2T. The efficiency of the magnetoelectric heating increases with the pressure decreasing when the pressure chenges in a range of 0.020.8Pa.

Large-area regular silicon nanowire arrays(SiNWs) were prepared on silicon substrate by electroless metal deposition method under hydrothermal conditions.Mechanism and effects of morphology control of SiNWs were studied.Morphologies and structures of SiNWs and Ag dendritic crystal were characterized by scanning electron microscopy(SEM) and X-ray diffraction(XRD).The results showed that morphology of SiNWs could be influenced by solution ratio,temperature and reacting time of hydrothermal system.Large-area SiNWs,which the length is 30-50 μm and the diameter is about 200nm,can be obtained on condition that temperature is 50℃,and concentrations of HF and AgNO3 are 4.6 and 0.02mol/L,respectively.The electroless metal deposition method is a kind of simple,moderate technology for preparation of silicon nanowires and SiNWs.

With continued scaling of complementary metal-oxide-silicon (CMOS) technology, numerous challenges have arisen making it difficult to progress with. These challenges include the increase of integrated circuit complexity, non-recoverable expenses, frequency and power density. Nanotechnologies are expected to take the forefront of continuing the technological revolution. In this work, a novel model-based latency/area analysis and optimization method for the newly proposed Asynchronous Nanowire Reconfigurable Crossbar Architecture (ANRCA) is presented and validated. ANRCA is based on a self-timed logic referred to as the Null Convention Logic (NCL). There is no global clocking and clock distribution network, all failure modes related to timing will be either eliminated or relaxed. The proposed architecture is anticipated to have higher manufacturability and robustness that are critical factors in nanoscale systems due to the nondeterministic nature of nanoassemblies and also suitable computing frameworks for asynchronous nanoscale communication networks. In order to facilitate efficient programming and flexible reconfiguration, a new hierarchical reconfigurable architecture for ANRCA is also proposed. Various configurable logic block structures have been considered and also their programming and reconfiguration issues are discussed. The proposed measurement and optimization method can be used to estimate area and latency measurements for different configurable logic blocks and also applied to find the optimal structure for the given arbitrary logic to map.

In this work, a novel asynchronous combinational S-Box (substitution box) design for AES (Advanced Encryption Standard) cryptosystems is proposed and validated. The S-Box is considered as the most critical component in AES crypto-circuits since it consumes the most power and leaks the most information against side-channel attacks. The proposed design is based on a delay-insensitive logic paradigm known as Null Convention Logic (NCL). The proposed NCL S-Box provides considerable benefits over existing designs since it consumes less power therefore suitable for energy-constrained mobile crypto-applications. It also emits less noise and has flatter power peaks therefore leaks less information against side-channel attacks such as differential power/noise analysis. Functional verification, analog simulation and power measurement of NCL S-Box have been done using Mentor Graphics EDA (Electronic Design Automation) tools to assure low-power side-channel attack-resistant operation of the proposed clock-free AES S-Box design.