Experimental characteristics and evidence of differences in the optical properties of multiple quantum well structures grown on (511)B‐ and (100)‐GaAs substrates are presented. It is shown that residual background ...
Experimental characteristics and evidence of differences in the optical properties of multiple quantum well structures grown on (511)B‐ and (100)‐GaAs substrates are presented. It is shown that residual background impurities do not behave in the same manner for similar structures grown on the two surfaces. It is also shown that the hole effective mass in the (511)B‐based structures is different from that in similar structures on (100) surfaces.
A particular class of processes defined on dyadic trees is treated. Three algorithms are given for optimal estimation/reconstruction for such processes: one reminiscent of the Laplacian pyramid and making efficient us...
详细信息
A particular class of processes defined on dyadic trees is treated. Three algorithms are given for optimal estimation/reconstruction for such processes: one reminiscent of the Laplacian pyramid and making efficient use of Haar transforms, a second that is iterative in nature and can be viewed as a multigrid relaxation algorithm, and a third that represents an extension of the Rauch-Tung-Striebel algorithm to processes on dyadic trees. The last involves a discrete Riccati equation, which in this case has three steps: prediction, merging and measurement update. Related work and extensions are briefly discussed.< >
The authors use methods of stochastic approximation to convert iterative algorithms for maximizing the Kullback-Liebler information measure (1959) into sequential algorithms. Special attention is given to the case of ...
详细信息
The authors use methods of stochastic approximation to convert iterative algorithms for maximizing the Kullback-Liebler information measure (1959) into sequential algorithms. Special attention is given to the case of incomplete data, and a variety of algorithms are presented to deal with situations of that kind. The authors consider the application of these algorithms to the identification of finite-impulse-response (FIR) systems.< >
Kerr electrooptic field mapping measurements were made in liquid nitrogen at 70 psi and -177 degrees C. A sensitive measurement technique was used whereby a small-signal AC voltage was superimposed on a DC level. The ...
详细信息
Kerr electrooptic field mapping measurements were made in liquid nitrogen at 70 psi and -177 degrees C. A sensitive measurement technique was used whereby a small-signal AC voltage was superimposed on a DC level. The nonlinear optical effect then gave an optical signal with a DC level and AC harmonic at the same frequency as the AC voltage. The amplitude of the AC optical signal was proportional to the local electric field and was measured with a lock-in amplifier. For 6330-nm-wavelength light the Kerr constant was measured to be B approximately=10/sup -16/ m/V/sup 2/. Steady-state electric fields between parallel stainless steel electrodes of gap 7 mm and area 31.6 cm/sup 2/ were shown to be essentially uniform for field strengths up to 90 kV/cm with no significant space charge distortion. The DC voltage-current characteristic was also measured and found to be nonohmic, reaching constant current of approximately=13 nA over the voltage range of approximately=30-60 kV.< >
The application of multigrid methods to a class of discrete-time, continuous-state, discounted, infinite-horizon dynamic programming problems is studied. The authors analyze the computational complexity of computing t...
详细信息
The application of multigrid methods to a class of discrete-time, continuous-state, discounted, infinite-horizon dynamic programming problems is studied. The authors analyze the computational complexity of computing the optimal cost function to within a desired accuracy of Ε, as a function of Ε and the discount factor α. Using an adversary argument, they obtain lower bound results on the computational complexity for this class of problems. They also provide a multigrid version of the successive approximation algorithm whose requirements are (as a function of α and Ε) within a constant factor from the lower bounds when a certain mixing condition is satisfied. Hence the algorithm is optimal.
A solution is presented to the L1 minimization problem for plants with commensurate delays. In the special case where the weight has one pole, the problem can be solved by a single linear programming problem. Other sp...
详细信息
A solution is presented to the L1 minimization problem for plants with commensurate delays. In the special case where the weight has one pole, the problem can be solved by a single linear programming problem. Other special cases are also presented. A method for computing the optimal performance and a characterization of minimizing solutions are given.
In the analog VLSI implementation of neural systems, it is sometimes convenient to build lateral inhibition networks by using a locally connected on-chip resistive grid. A serious problem of unwanted spontaneous oscil...
详细信息
In the analog VLSI implementation of neural systems, it is sometimes convenient to build lateral inhibition networks by using a locally connected on-chip resistive grid. A serious problem of unwanted spontaneous oscillation often arises with these circuits and renders them unusable in practice. The authors report a design approach that guarantees that such a system will be stable, even though the values of designed elements in the resistive grid can be imprecise and the location and values of parasitic elements can be unknown. The method is based on a mathematical analysis using Tellegen's theorem and the Popov criterion. The criteria are local in the sense that no overall analysis of the interconnected system is required for their use, empirical in the sense that they involve only measurable frequency response data on the individual cells, and robust in the sense that they are not affected by unmodeled parasitic resistances and capacitances in the interconnect network.
作者：
Tsitsiklis, John N.MIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA
Summary form only given. The author has studied an asynchronous version of the Bellman-Ford algorithm for computing the shortest distances from all nodes in a network to a fixed destination. It is known that this algo...
详细信息
Summary form only given. The author has studied an asynchronous version of the Bellman-Ford algorithm for computing the shortest distances from all nodes in a network to a fixed destination. It is known that this algorithm has (in the worst case) exponential (in the size of the underlying graph) communication complexity. The author has obtained results indicating that its expected (in a probabilistic sense) communication complexity is actually polynomial, under some reasonable probabilistic assumptions. He has shown that a recently introduced method for asynchronous simulation with rollback contains the Bellman-Ford algorithm as a special case, and he has deduced that the rollback method also has exponential communication complexity. The author has also investigated whether (under certain probabilistic assumptions and/or modifications of the simulation algorithm) the communication complexity becomes polynomial.
A 2- mu m BiCMOS process designed for 10-V analog/digital applications is described. This process utilizes selective epitaxial growth to integrate a vertical n-p-n bipolar structure with an estimated cutoff frequency ...
详细信息
A 2- mu m BiCMOS process designed for 10-V analog/digital applications is described. This process utilizes selective epitaxial growth to integrate a vertical n-p-n bipolar structure with an estimated cutoff frequency of 5 GHz and nonoptimized vertical p-n-p structure into a 2- mu m CMOS process with a poly-to-n/sup +/ capacitors. The insertion of the bipolar structures is accomplished with only two added masking steps and with no change to the critical process parameters which determine the performance of the MOS transistors.
Simple photometric relationships governed the previous imaging systems in film and video applications. More recently the introduction of wide-band image sensors, particularly those based upon silicon, has required gre...
详细信息
暂无评论