刀具参数对加工表面粗糙度影响的研究

通过车削加工试验和数据测量,研究了刀具参数及刀具磨损量对加工表面粗糙度的影响。应用Matlab计算得出刀具参数变化和刀具磨损量对加工表面粗糙度的定量关系,为加工时选用刀具参数及控制刀具磨损量提供理论依据。     

Cavity length and absorption dependent longitudinal beat in iodine photodissociation laser

As the cavity length of the iodine photodissociation laser (iodine PDL) is varied, the number of neighboring coherent modes increases and the time-dependent mode-competition effect gives rise to typical changes in the pulse shape. The ratio of the number of all coherent modes to that of all oscillating modes is found to be as high as 80 percent when the cavity length is 450 cm. The frequency width in which the neighboring modes are coherent is approximately 0.1 GHz for all cavity lengths used. The effect of a BDN absorber placed in the cavity is distinct in the shorter cavities.     

Improved Scalar Multiplication on Elliptic Curves Defined over F2mn

We propose two improved scalar multiplication methods on elliptic curves over F_qn where q = 2^m using Frobenius expansion. The scalar multiplication of elliptic curves defined over subfield F_q can be sped up by Frobenius expansion. Previous methods are restricted to the case of a small m. However, when m is small, it is hard to find curves having good cryptographic properties. Our methods are suitable for curves defined over medium‐sized fields, that is, 10 ≤ m ≤ 20. These methods are variants of the conventional multiple‐base binary (MBB) method combined with the window method. One of our methods is for a polynomial basis representation with software implementation, and the other is for a normal basis representation with hardware implementation. Our software experiment shows that it is about 10% faster than the MBB method, which also uses Frobenius expansion, and about 20% faster than the Montgomery method, which is the fastest general method in polynomial basis implementation.     

Performance of Efficient Signal Detection for LED-ID Systems

In this paper, effects of reader-to-reader interference are investigated for LED identification (LED-ID) system in a multi-reader environment. The LED-ID readers typically use different channels to avoid collision between readers. However, in-channel collision usually happens in terms of interrogation range. A reader-to-reader interference scenario is proposed, and nominal interrogation range of a desired reader is derived from this model. In order to evaluate the LED-ID reader-to-reader interference quantitatively, an efficient detection scheme is proposed and simulated by employing spreading sequence. The spreading sequence is inserted between each user’s frame formats. In the receiver, the desired signal is detected by using correlation among inserted spreading sequences. From simulation results, it is confirmed that the proposed scheme is very effective to enhance reliability of LED-ID communication systems.     

弹底过载存储记录仪

为获取弹丸在膛内的加速度,设计了一种能承受高压、高过载的微小型存储测试仪。它由单片机和CPLD作为主控芯片、高速FIFO作为缓存与NAND flash为存储介质,以橡胶作为电路模块与外壳的缓冲材料。采用有限元软件ANSYS/LSDYNA对冲击过程进行了数值模拟,并经155mm火炮实测验证。记录仪成功获取了膛内弹底加速度,并承受住了弹丸出口31000g的过载。     

LTE小区间干扰抑制技术介绍及比较

主要介绍了LTE目前采用的干扰抑制的方法,说明了这些干扰抑制方法对抑制小区间干扰,提高系统性能的作用,并比较了不同方法的优劣。     

溶胶-凝胶法制备ITO薄膜及其光电性能的研究

采用溶胶-凝胶工艺,用提拉法在玻璃基底上制备了ITO透明导电薄膜。使用四探针测试仪和紫外可见光分光光度计测量薄膜的方阻和透过率,并采用XRD、SEM等测试手段对薄膜的晶体结构、表面形貌进行了表征。结果表明,掺锡比例和热处理温度对薄膜的导电性具有重要影响,在掺Sn量为15%(原子分数比)、450℃热处理时薄膜的方阻最小;薄膜的透过率曲线随掺锡比例的增加向紫外方向移动。随着热处理时间、镀膜层数的增加,薄膜的方阻先减小,最后趋于一稳定值,在可见光范围内薄膜的透过率变化较小。     

Reversible Conversion Reactions and Small First Cycle Irreversible Capacity Loss in Metal Sulfide‐Based Electrodes Enabled by Solid Electrolytes

Solid‐state batteries can potentially enable new classes of electrode materials which are unstable against liquid electrolytes. Here, SnS nanocrystals, synthesized by a wet chemical method, are used to fabricate a Li‐ion electrode, and the electrochemical properties of this electrode are examined in both solid and liquid electrolyte designs. The SnS‐based solid‐state cell delivers a capacity of 629 mAh g^?1 after 100 cycles and exhibits an unprecedentedly small irreversible capacity in the first cycle (8.2%), while the SnS‐based liquid cell shows a rapid capacity decay and large first cycle irreversible capacity (44.6%). Cyclic voltammetry (CV) experiments show significant solid electrolyte interphase (SEI) formation in the liquid cell during the first discharge while SEI formation by electrolyte reduction in the solid‐state cell appears negligible. Along with CV, X‐ray photoelectron spectroscopy and energy dispersive spectroscopy are used to investigate the differences between the solid‐state and liquid cells. The reaction chemistry of SnS in solid‐state cells is also studied in detail by ex situ X‐ray diffraction and X‐ray absorption spectroscopy. The overarching findings are that use of a solid electrolyte suppresses materials degradation and electrolyte reduction which leads to a small first cycle irreversible capacity and stable cycling.     

A Discrete‐Amplitude Pulse Width Modulation for a High‐Efficiency Linear Power Amplifier

A new discrete‐amplitude pulse width modulation (DAPWM) scheme for a high‐efficiency linear power amplifier is proposed. A radio frequency (RF) input signal is divided into an envelope and a phase modulated carrier. The low‐frequency envelope is modulated so that it can be represented by a pulse whose area is proportional to its amplitude. The modulated pulse has at least two different pulse amplitude levels in order that the duty ratios of the pulse are kept large for small input. Then, an RF pulse train is generated by mixing the modulated envelope with the phase modulated carrier. The RF pulse train is amplified by a switching‐mode power amplifier, and the original RF input signal is restored by a band pass filter. Because duty ratios of the RF pulse train are kept large in spite of a small input envelope, the DAPWM technique can reduce loss from harmonic components. Furthermore, it reduces filtering efforts required to suppress harmonic components. Simulations show that the overall efficiency of the pulsed power amplifier with DAPWM is about 60.3% for a mobile WiMax signal. This is approximately a 73% increase compared to a pulsed power amplifier with PWM.     

Highly Stretchable and Sensitive Strain Sensors Using Fragmentized Graphene Foam

Stretchable electronics have recently been extensively investigated for the development of highly advanced human‐interactive devices. Here, a highly stretchable and sensitive strain sensor is fabricated based on the composite of fragmentized graphene foam (FGF) and polydimethylsiloxane (PDMS). A graphene foam (GF) is disintegrated into 200–300 μm sized fragments while maintaining its 3D structure by using a vortex mixer, forming a percolation network of the FGFs. The strain sensor shows high sensitivity with a gauge factor of 15 to 29, which is much higher compared to the GF/PDMS strain sensor with a gauge factor of 2.2. It is attributed to the great change in the contact resistance between FGFs over the large contact area, when stretched. In addition to the high sensitivity, the FGF/PDMS strain sensor exhibits high stretchability over 70% and high durability over 10 000 stretching‐releasing cycles. When the sensor is attached to the human body, it functions as a health‐monitoring device by detecting various human motions such as the bending of elbows and fingers in addition to the pulse of radial artery. Finally, by using the FGF, PDMS, and μ‐LEDs, a stretchable touch sensor array is fabricated, thus demonstrating its potential application as an artificial skin.