Efficient reverse converter design for the new four-moduli set {22n, 2n + 1, 2n/2 + 1, 2n/2 – 1}

Abstract

This paper presents a new four-moduli set {2²ⁿ, 2ⁿ + 1, 2^n/2 + 1, 2^n/2 – 1} (n even). According to new Chinese remainder theorem 1, an efficient algorithm is derived for converting four residue numbers to binary. Then, the converter architecture is designed using shorter bit-width carry propagate adders to improve the hardware performance considerably. Compared with existing converters for related four-moduli sets, the proposed converter shows higher speed and lower power consumption. The proposed converter design with 64-bit width has been implemented on the basis of the Taiwan Semiconductor Manufacturing Company 90-nm CMOS process. The chip area is 1622 × 1657 μm², and the working frequency is 116 MHz. The experimental results show that the proposed design achieves more than 26.9 and 18.4% savings in delay and power consumption, respectively. The converter also saves at least 39% in AD² (area × delay²).     

Augmenting 2 n−1 Designs

After a 2 ^n?k fractional factorial has been analysed, an experimenter may wish to carry out a further fraction to improve some estimates and break chains of aliases. The problem of augmenting a 2 ^n?1 half replicate by a nonoverlapping 2 ^n?k design is discussed. In each alias set for the 2 ^n?k fraction the effects occur in pairs as aliases from the half replicate. If only one of these pairs in a given alias set contains two nonnegligible effects, then that chain is broken. If more than one pair has both effects nonnegligible, no chains are broken. Procedures are given for augmenting four-letter plans for four or six factors.     

Crystal structure and anisotropy of iodine-intercalated Bi2Sr2Ca n−1Cu n O x

The electronic state and structural configuration of the intercalated iodine species in stage-1, I-Bi₂Sr₂Ca _n?1Cu _n O _x (n = l, 2), have been studied through polarization-resolved Raman and¹²⁹I Mössbauer spectroscopy. The polarization dependence of the Raman spectra and the Mössbauer measurement confirmed the dominant species to be triiodide ions, I ₃ ^? , with alignment of these linear molecules either along thea- orb-axis in the host crystals. Transport measurements such as thermoelectric power and Hall coefficient clearly indicated that hole carriers are doped into the CuO₂ planes upon intercalation, by whichT _c of the host superconductor is changed. Furthermore, based on resistivity measurements in a magnetic field, we suggest that the iodine intercalation leads to a decrease of the anisotropy both in normal and superconducting states, suppressing the extremely two-dimensional character of the Bi₂Sr₂Ca _n?1Cu _n O _x systems.     

ZrO2(n)/SiC(n)-MoSi2纳米复合陶瓷中纳米颗粒的均匀分散

本文探讨了在pH值一定的情况下,不同分散剂、不同分散介质对纳米ZrO2、纳米SiC的分散效果的影响,并考察了不同表面处理方法对纳米SiC颗粒分散性的影响.研究结果表明:以PEG为分散剂、水为分散介质可以有效地分散纳米ZrO2和纳米SiC,并能与基体MoSi2粉末均匀混合;采用550℃、2h的煅烧工艺处理纳米SiC可有效改善其分散性.     

Cu/ n2TiO 2/ PBO复合纤维的制备

以 PBO纤维为基体 , 采用浸渍涂覆法在 PBO纤维表面包覆纳米 TiO 2膜 , 采用化学镀法将 Cu沉积到纳米 TiO 2膜表面 , 制备了 Cu/ n2 TiO 2/ PBO复合纤维 , 研究了影响纳米 TiO 2沉积速率和 Cu 沉积速率的主要因素。结果表明 , 纳米 TiO 2与偶联剂的浓度配比是影响纳米 TiO 2包膜形成的主要因素 , 当纳米 TiO 2与偶联剂浓度配比为 1∶1. 2时 , 制备的 n2TiO 2/ PBO复合纤维界面结合力较好 , 且纳米 TiO 2包覆层比较均匀。影响化学镀铜- 1 的主要因素有镀液成分、 反应时间和反应温度。在镀液成分的浓度配比为 CuSO 4·5H 2O 12 g ·L 、KNaC 4H 4 - 1 - 1 - 1O 68 g·L 、HCHO 6 mL ·L 和 NaOH 10 g·L , 反应温度 50℃, 镀铜时间 20 min的条件下 , 制备了负载均匀 , 界面结合力较好的 Cu/ n2 TiO 2/ PBO复合纤维。     

Critical thermistors based on VnO2n−1 (n=3−6)

New types of critical thermistors are proposed, based on V₃O₅, V₄O₇, V₅O₉, and V₆O₁₁. It is shown that they can be prepared from Magnelli-phase single crystals, which do not decompose during the phase change. Volt-ampere characteristics and switching voltage-temperature curves were obtained.     

MoTe2 p–n Homojunctions Defined by Ferroelectric Polarization

Doped p–n junctions are fundamental electrical components in modern electronics and optoelectronics. Due to the development of device miniaturization, the emergence of two-dimensional (2D) materials may initiate the next technological leap toward the post-Moore era owing to their unique structures and physical properties. The purpose of fabricating 2D p–n junctions has fueled many carrier-type modulation methods, such as electrostatic doping, surface modification, and element intercalation. Here, by using the nonvolatile ferroelectric field polarized in the opposite direction, efficient carrier modulation in ambipolar molybdenum telluride (MoTe₂) to form a p–n homojunction at the domain wall is demonstrated. The nonvolatile MoTe₂ p–n junction can be converted to n–p, n–n, and p–p configurations by external gate voltage pulses. Both rectifier diodes exhibited excellent rectifying characteristics with a current on/off ratio of 5 × 10⁵. As a photodetector/photovoltaic, the device presents responsivity of 5 A W⁻¹, external quantum efficiency of 40%, specific detectivity of 3 × 10¹² Jones, fast response time of 30 µs, and power conversion efficiency of 2.5% without any bias or gate voltages. The MoTe₂ p–n junction presents an obvious short-wavelength infrared photoresponse at room temperature, complementing the current infrared photodetectors with the inadequacies of complementary metal-oxide-semiconductor incompatibility and cryogenic operation temperature.     

Exchange Interactions and Ferromagnetism of Pr_(n+1)Co_(3n+5)B_(2n)-type Compounds

In present investigation exchange interactions of Pr_(n+1)Co_(3n+5)B_(2n)-type compounds have been evalu-ated in the light of molecular-field theory. The exchange interactions and ferromagnetism in thesecompounds are discussed in terms of lattice parameters and interatomic distance between Co atom.     

Localized magnetism in YMn2 below the néel temperature

We have measured magnetic susceptibility, thermal expansion, electrical resistivity, and magnetoresistance of the intermetallic compound YMn₂. YMn₂ orders antiferromagnetically belowT _N 110 K. There is a large thermal hysteresis such that the ordering temperature isT _N =86 K on cooling andT _N =116 K on warming. This is a first-order phase transition from the paramagnetic to antiferromagnetic phase. Our electrical resistivity and magnetoresistance measurements in the ordered state show a localized magnetic moment for Mn atoms in YMn₂ belowT _N . The Mn moments collapse atT _N which is reflected in the sharp decrease in the thermal expansivity atT _N . AboveT _N the Mn moment gradually recovers with increasing temperature which is reflected as an increase in with increasing temperature in the paramagnetic state. This behavior atT>T _N could be described by weak itinerant electron magnetism.     

多孔 n2 HA/ PA26复合材料的制备及性能

采用注塑方法制备了多孔纳米磷灰石/聚酰胺26 (n2 HA/ PA26) 复合材料 , 采用 SEM、XRD、IR、 力学性能测试考察了多孔材料的性能。结果发现 : 多孔纳米磷灰石/聚酰胺26复合材料的孔隙分布均匀 , 贯通性良好 , 孔的尺寸约为 100～700μm , 平均孔径约 300～500μm , 大孔壁上有丰富的微孔 ; 所得多孔复合材料的孔隙率可控 , 总孔隙率最高可达 881 6 %; 多孔材料的总孔隙率降低 , 则开孔率随之降低 ; 多孔纳米磷灰石/聚酰胺26 复合材料的抗压强度为 1. 1～15. 6 MPa , 压缩模量为 0. 4～1. 4 GPa ; 在总孔隙率相近的条件下 , 多孔材料的抗压强度随 n2 HA质量分数增加而升高; 发泡剂和发泡过程对组成纳米磷灰石/聚酰胺26复合材料的两组元材料的性质和结构无影响。这种多孔材料可望作为人体非承重部位的植入骨修复体和组织工程支架使用。     

关于2~2~k值n元逻辑函数的几何图象模型与图象分析初探

本文建立了由2值向2~(2~k)值(k∈{0,1,2…})拓广的多值n维逻辑空间几何图象模型及其图象分析基础。主要内容有:(1)2~(2~k)值n维逻辑空间的结构与几何图象模型;(2)2~(2~k)值n元逻辑函数、范式及0—1方程的图象分析;(3)用图象分析法求2~(2~k)值n元逻辑方程的再生解。     

Lateral 2D WSe2 p–n Homojunction Formed by Efficient Charge-Carrier-Type Modulation for High-Performance Optoelectronics

As unique building blocks for next-generation optoelectronics, high-quality 2D p–n junctions based on semiconducting transition metal dichalcogenides (TMDs) have attracted wide interest, which are urgent to be exploited. Herein, a novel and facile electron doping of WSe₂ by cetyltrimethyl ammonium bromide (CTAB) is achieved for the first time to form a high-quality intramolecular p–n junction with superior optoelectronic properties. Efficient manipulation of charge carrier type and density in TMDs via electron transfer between Br⁻ in CTAB and TMDs is proposed theoretically by density functional theory (DFT) calculations. Compared with the intrinsic WSe₂ photodetector, the switching light ratio (I_light/I_dark) of the p–n junction device can be enhanced by 10³, and the temporal response is also dramatically improved. The device possesses a responsivity of 30 A W⁻¹, with a specific detectivity of over 10¹¹ Jones. In addition, the mechanism of charge transfer in CTAB-doped 2D WSe₂ and WS₂ are investigated by designing high-performance field effect transistors. Besides the scientific insight into the effective manipulation of 2D materials by chemical doping, this work presents a promising applicable approach toward next-generation photoelectronic devices with high efficiency.     

Critical current densities and irreversibility fields of high-Tc superconductors AuBa2Can−1CunO2n+3 (n=3,4) prepared under high pressure

Critical current densities (J_c) and irreversibility fields (B_irr) of high-T_c superconductors AuBa₂Ca_n−1Cu_nO_2n+3 [Au-12(n−1)n, n=3,4] prepared under high pressure were determined from the hysteresis in DC magnetization loop. Both the J_c and B_irr values of the Au-1234 phase were larger than those of Hg- and Bi-based cupurate superconductors, but smaller than those of the Y-123 superconductor. This result suggests that the electronic structure of Au-1234 is less anisotropic compared with the Hg- and Bi-phases. The Au-1223 phase showed very small J_c values corresponding to its small superconducting volume fraction.     

Infrared spectra of bismuth family of superconductors Bi2Sr2Can−1CunO4+2n+y

FTIR spectra of bismuth family of superconductors are studied. Polycrystalline samples of bismuth superconductors are prepared choosing an off-stoichiometric composition for phase stabilisation and reproducibility. Vibrational modes are strongly affected by the holes introduced into the CuO planes. Mid IR spectra of the Bismuth system was recorded using Bruker IFS 66v and the high frequency oxygen vibrations of the system is discussed based on the factor group analysis for both symmorphic and non-symmorphic space groups I4/mmm, F_mmm and A_maa of different structures based on the modulated superstructure.     

p—聚乙炔／n—SnO2异质结光伏特电池

用改进的Ｎａａｒｍａｎｎ方法，在ｎ型ＳｎＯ２基片上直接合成聚乙炔，用碘液相掺杂，制成ｐ－聚乙炔／ｎ－ＳｎＯ２异质结光伏特电池。用功率连续可调的氩离子激光器作光源，测量了电池的光伏特－电流关系曲线，并由此计算出电池的转换效率。笔者发现，对未掺杂的电池，光电转换效率很低，而掺杂可以大大提高电池的短路电流和转换效率。     

La掺杂n型Mg2Si基半导体的热电性能研究

采用感应熔炼然后热压的方法制备了La掺杂Mg2Si基热电材料Mg2-xLaxSi(x=0、0.002、0.005、0.010、0.015).La在Mg2Si中占Mg位,当x≥0.005时,出现第二相LaMg.性能测试表明,Mg2-xLaxSi的导电类型为n型,Seebeck系数的绝对值随La含量的增多而减小,电导率和热导率均随La含量的增多而增大,在测试温度范围内,Mg1.995La0.005Si具有最高的ZT值,在774K温度下达到0.42.     

p－聚乙炔／n－SnO_2异质结光伏特电池

用改进的Ｎａａｒｍａｎｎ方法，在ｎ型ＳｎＯ_２基片上直接合成聚乙炔，用碘液相掺杂，制成ｐ－聚乙炔／ｎ－ＳｎＯ_２异质结光伏特电池。用功率连续可调的氩离子激光器作光源，测量了电池的光伏特－电流关系曲线，并由此计算出电池的转换效率。笔者发现，对未掺杂的电池，光电转换效率很低，而掺杂可以大大提高电池的短路电流和转换效率。     

Properties of n × n square arrays of proximity effect bridges

We have studied the I-V characteristics, the dc resistance at the origin R(T), and the critical current I _c (T) of arrays consisting of n × n (n = 10, 20, 30, and 40) In squares separated by Au/In regions. The superconducting squares have side d _s (In) from 7.5 to 15 m and d _N (Au/In) from 2.5 to 11 m. These devices show two transition temperatures in their R(T) curve; one at T _cG near T _c (In) and another one at T _c ^* above T _c (Au/In). The I-V curves for each temperature region resemble recent published results on NbN granular films. These arrays follow a formalism proposed by Wolf, Gubser, and Imry to describe the transition to a resistanceless state at T _c ^*. The measured values of I _c (T) are larger than expected from n noninteracting Bardeen-Johnson junctions in parallel, although the exponential behavior in temperature is followed. They are compatible with the idea of bands in the quasiparticle spectrum in the Au/In regions. Deviations in I _c (T) from an exponential behavior in T near T _c ^* have been analyzed by applying to SNS arrays ideas developed for phase transitions in SIS arrays. Evidence that at T _c ^* we may be observing a phase transition at T _cJ due to the Josephson coupling between In squares exists but it needs the development of theoretical work to be put on more solid grounds.Supported by the Swiss National Science Foundation.     

Carbon Cage Vibrations of M@C82 and M2@C2 n (M = La,Ce; 2n = 72, 78, 80): The Role of the Metal Atoms

Infrared spectra of La₂@C₈₀ and a series of Ce-based endohedral metallofullerenes (EMFs), including Ce@C₈₂, Ce₂@C₇₂, Ce₂@C₇₈, and Ce₂@C₈₀ are reported. DFT calculations are used for their thorough analysis and assignment. The vibrations of the fullerene cages in all studied EMFs differ from those of their empty, charged cage analogues. Furthermore, EMFs with the same carbon cage but different type of encapsulated species also show significant differences in their cage vibrational patterns. These phenomena are explained by a different coupling of the vibrational modes as well as by the different charge distributions in EMFs and empty, isostructural fullerene anions.     

Net Holes and Superconductivity in the Members with n ≥ 3 of Homologous Series, Tl- and Hg-m2(n-l)n

All the Tl- and Hg-based superconducting cuprates can be classified as members of Tl/Hg-m2(n-l)n homologous series, with m being 1 or 2, and n increasing even up to 7. In the phases with n 3, holes may be inhomogeneously distributed between outer (Coordination Number = 5) and inner (CN = 4) CuO₂ planes. In each series T _c increases as n increases from 2 to 3, and then either saturates or slowly decreases with n > 3, proposing that the CuO₂ planes predominantly controlling the value of T _c are different in the n 3 phases from those in the structures with n = 1 (CN = 6) or 2 (CN = 5). Estimation of the distribution of holes between the inequivalent CuO₂ planes utilizing existing crystallographic data and a bond-valence-sum calculation method, results in a somewhat surprising conclusion that the holes are confined in the innermost CuO₂ planes. On the other hand, the result agrees with the empirical believe that the flatter the CuO₂ planes the higher the T _c..