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41.
Mantooth B.A. Weiss P.S. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2003,91(11):1785-1802
One of the ultimate miniaturizations in nanotechnology is molecular electronics, where devices will consist of individual molecules. There are many complications associated with the use of molecules in electronic devices, such as the electronic perturbations in the molecule associated with being bonded to an electrode, how electrons traverse the metal-molecule junction, and the difficulty of macroscopically addressing single to very few molecules. Whether fabricating a test structure or a usable device, the use of self-assembly is fundamental to the fabrication of molecular electronic devices. We will discuss how to fabricate self-assembled monolayers into test assemblies and how to use intermolecular interactions to direct molecules into desired positions to create nanostructures and to connect functional molecules to the outside world. These assemblies serve as test structures for measurements on single or bundled molecules. The development of several experimental techniques, including various scanning probes, mercury drop junctions, break junctions, nanopores, crossed wires, and other techniques using nanoparticles have enabled the ability to test these structures and make reproducible measurements on single molecules. Many of these methods have been developed to test molecules with potential for integration into devices such as oligo (phenylene-ethynylene) molecules and other /spl pi/-conjugated molecules, in ensemble or single-molecule measurements. 相似文献
42.
Nobel A.B. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2003,49(1):83-98
This paper considers several aspects of the sequential prediction problem for unbounded, nonstationary processes under pth power loss /spl lscr//sub p/(u,v)=|u-v|/sup p/, 1
相似文献
43.
Nucleation and growth mechanisms and kinetics of crystals of an amino acid salt were investigated in a methanol‐water system by measuring and evaluating the induction time as a function of the supersaturation ratio and temperature in batch salting out crystallization experiments. Discrimination between the possible crystallization mechanisms, and estimation of the kinetic parameters were carried out using nonlinear parameter identification. The results concerning the growth mechanism obtained were checked additionally by measuring the induction time as a function of number density of seed crystals. 相似文献
44.
This paper reports on the stability analysis of one member of a dual-channel resonant DC-DC converter family. The study is confined to the buck configuration in symmetrical operation. The output voltage of the converter is controlled by a closed loop applying constant-frequency pulsewidth modulation. The dynamic analysis reveals that a bifurcation cascade develops as a result of increasing the loop gain. The trajectory of the variable-structure piecewise-linear nonlinear system pierces through the Poincare plane at the fixed point in state space when the loop gain is small. For stability criterion the positions of the characteristic multipliers of the Jacobian matrix belonging to the Poincare map function defined around the fixed point located in the Poincare plane is applied. In addition to the stability analysis, a bifurcation diagram is developed showing the four possible states of the feedback loop: the periodic, the quasi-periodic, the subharmonic, and the chaotic states. Simulation and test results verify the theory. 相似文献
45.
This paper presents the evolution of low-frequency, high-power transcontinental transmission, starting from the first successful transatlantic link from Poldhu up to the Italian transcontinental station of Coltano. The trend toward higher and higher transmitting power, and the dead end into which wireless was heading if it were not for research in the higher frequency ranges, are pointed out. 相似文献
46.
Reducible rank codes and their applications to cryptography 总被引:2,自引:0,他引:2
Gabidulin E.M. Ourivski A.V. Honary B. Ammar B. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2003,49(12):3289-3293
We present a new family of so-called reducible rank codes which are a generalization of rank product codes . This family includes maximal rank distance (MRD) codes for lengths n>N in the field F/sub N/. We give methods for encoding and decoding reducible rank codes. A public key cryptosystem based on these codes and on the idea of a column scrambler is proposed. The column scrambler "mixes" columns of a generator (parity-check) matrix of a code. It makes the system more resistant to structural attacks such as Gibson's attacks. Possible attacks on the system are thoroughly studied. The system is found to be secure against known attacks for public keys of about 16 kbits and greater. 相似文献
47.
48.
求解二维结构-声耦合问题的一种直接方法 总被引:1,自引:1,他引:0
本文基于传递矩阵法(TMM)和虚拟边界元法(VBEM),提出了一种求解在谐激励作用下二维结构-声耦合问题的直接法。文中对任意形状的二维弹性环建立了一阶非齐次运动微分方程组,便于用齐次扩容精细积分法求解,对于含有任意形状孔穴的无穷域流体介质的Helmholtz外问题,采用复数形式的Burton-Miller型组合层势法建立了虚拟边界元方程,保证了声压在全波数域内存在唯一解。根据叠加原理并结合最小二乘法,提出了一种耦合方程的直接解法,由于该方法不存在迭代过程,因而具有较高的计算精度和效率。文中给出了二个典型弹性环在集中谐激励力作用下声辐射算例,计算结果表明本文方法较通常采用的混合FE/BE法更为有效。 相似文献
49.
B. Delworth Gardner 《国际水资源开发杂志》2003,19(1):7-19
For more than half a century, in nearly all western states, the regulatory agencies (the State Engineer or equivalent) used impairment of other water rights as the primary criterion for approving or rejecting change applications to move water to higher-valued uses. In recent years, however, protests to change applications have been brought by 'stakeholders' who do not own water rights, but who argue that they are affected by water transfers. Under the impairment rule, these parties do not have statutory standing to protest successfully. But they have brought legal suits to block transfers, and the courts have considered whether additional criteria involving 'impacts on social welfare' are needed to evaluate transfers. State Supreme Court rulings on such suits in Utah and Nevada are reviewed as prototype cases. The Utah court held that additional 'social welfare' criteria must be utilized by the State Engineer in evaluating change applications, whereas the Nevada court held that such criteria were already incorporated in existing water statutes and administrative practice. The critical question raised in the paper is whether existing state regulatory agencies can effectively implement a real 'social welfare' criterion to evaluate change applications. The conclusion is that they probably cannot, and that if they try, water allocations will be politicized to a much greater extent than they are now, and efficient market transfers will be impeded if not completely prevented. 相似文献
50.
A biochar from casein and its properties 总被引:2,自引:0,他引:2
A biochar was prepared by pyrolysis of casein. A helium and mercury porosimeter were used to measure the true and apparent densities of the chars respectively, elemental and IR analysis were used to characterize the chemical composition of char. A SEM was used to observe the char surfaces in order to verify the presence of porosity. The biochar has 9.02% of nitrogen, content of porosity is 20%. The experimental results show that it is possible to prepare chars with relatively high porosity from casein for the further preparation of activated carbon. 相似文献