We have measured the temperature dependence of the gain characteristics in 1.3-µm AlGaInAs/InP strained multiple-quantum-well (MQW) semiconductor lasers using Hakki-Paoli method. By measuring the temperature dependences of the peak gain value and the gain peak wavelength, we evaluated the temperature dependences of the threshold current and the oscillation wavelength, respectively. The small temperature dependence of the threshold current in AlGaInAs/InP lasers is caused by the small temperature dependence of the transparency current density, which is represented by the characteristic temperature TJtr of 116 K. In AlGaInAs/InP high T0 lasers, the temperature dependence of the oscillation wavelength is slightly larger than that in GaInAsP/InP lasers because of the larger temperature dependence of bandgap wavelength 0.55 nm/K.

This paper describes the design and results of low cost integrated CMOS local and remote temperature sensors with digital outputs. No trimming is needed to obtain good temperature linearity, so that only one-temperature calibration is needed which greatly reduces testing cost. The base-emitter voltage of the parasitic substrate bipolar transistor is used to measure the local temperature. A diode-connected external bipolar transistor is used to measure the remote temperature. Chopper techniques were used to cancel the offset voltage of the op-amp, so that a precise bandgap voltage can be obtained without resistance trimming. A first order ΣΔ ADC was used to produce the digital output. The local and remote temperature sensors were realized in a 0.6 µm single-poly triple-metal CMOS technology with active area of 0.6 mm2 and 0.65 mm2, respectively. After calibration, the error is 1 for the local temperature sensor over the temperature range of -20 to 130, and 2 for the remote temperature sensor over the range of 0 to 120. The supply currents of the local and remote temperature sensors are 3.5 µA and 38 µA at 8 samples/s, respectively.

An improved pulse shaper is proposed which is able to control both the spatial and temporal profile of femtosecond light pulses. Our pulse shaper exploits the spatio-temporal coupling effect seen in pulse shapers. Its properties are numerically analyzed by application of the Wigner distribution function. We confirm that the spatio-temporal output pulse track dictates the differentiation of the phase mask; that the degree of spatio-temporal coupling is determined by the focal length ratio of the lenses in the pulse shaper; and that space to spatial-frequency chirp results from misalignment of lenses.

A proper design and analysis of future wideband wireless communication systems require an accurate radio channel model. This model is claimed to characterize both the spatial and temporal channel characteristics. This paper investigates the spatio-temporal channel modeling based on a ray-tracing approach. The temporal channels are characterized by a delay profile. The statistical median and fading-fluctuation range of delay profiles are predicted from ray tracing by incorporating the random phase approach. A high level of agreement between predicted results and measured ones is observed in the verification. The spatio-temporal channel impulse response (CIR) predicted from ray tracing is also transformed to have limited band-width and limited beam-width characteristics. The applicability of this transformation is also verified by the comparison with measurement. These verifications prepare the ground for the use of ray-tracing approaches to evaluate system performance in real environments.

A voltage mode logic device based on RF-Field-driven DC-SQUID (RFDS) using high-TC superconducting Josephson junctions has been proposed. RFDS produces large RF-induced steps, and the orders of steps are strongly selected by DC magnetic flux crossing the SQUID loop superposing with RF magnetic field. In this paper, we present the experimental results of RFDS fabricated by using YBCO grain boundary Josephson junctions. The results are evaluated with numerical simulations. The enhancement of RF-induced steps, the strong selection of step orders and the switching performance are demonstrated.

Spatio-temporal decorrelation is the task of eliminating correlations between associated signals in spatial domain as well as in time domain. In this paper, we present a simple but efficient adaptive algorithm for spatio-temporal decorrelation. For the task of spatio-temporal decorrelation, we consider a dynamic recurrent network and calculate the associated natural gradient for the minimization of an appropriate optimization function. The natural gradient based spatio-temporal decorrelation algorithm is applied to the task of blind deconvolution of linear single input multiple output (SIMO) system and its performance is compared to the spatio-temporal anti-Hebbian learning rule.

Recently, two approaches investigated indexing and retrieving videos. One approach utilized the visual features of individual objects, and the other approach exploited the spatio-temporal relationships between multiple objects. In this paper, we integrate both approaches into a new video model, called the Visual-Spatio-Temporal (VST) model to represent videos. The visual features are modeled in a topological approach and integrated with the spatio-temporal relationships. As a result, we defined rich sets of VST relationships which support and simplify the formulation of more semantical queries. An intuitive query interface which allows users to describe VST features of video objects by sketch and feature specification is presented. The conducted experiments prove the effectiveness of modeling and querying videos by the visual features of individual objects and the VST relationships between multiple objects.

Another high performance simulated annealing is proposed which we call widely stepping simulated annealing (WSSA). It flies from a starting high temperature to a finishing low temperature staying at only twenty or so temperatures to approach thermal equilibriums. We survey the phase transition in simulated annealing process and estimate the major cost variation (dEc) at the critical temperature. The WSSA uses a function (H(t)) that represents the probability for a hill-climbing with the dEc of cost increase to be accepted in Metropolis' Monte Carlo simulation at temperature t. We have applied the first version of WSSA to one dimensional transistor placement optimizations for several industrial standard cells, and compared its performance with simulated annealing with a geometrically scheduled cooling. The solutions by the WSSA are as good as, and sometimes much better than, the solutions by the simulated annealing, while the time consumption by the WSSA is properly under one 30th of that by the simulated annealing.

In computer science, concepts of resource such as data consumption and of time such as execution time are very important. Logical systems which can treat them have been applied in that field. Linear logic has been called a resource conscious logic. The expressive power is enough to describe a dynamic change in process environments. However, linear logic is not enough to treat a dynamic change in environments with the passage of time since it does not include a concept of time directly. A typical example is the relation between linear logic and Petri nets. It is well known that the reachability problem for Petri nets is equivalent to the provability for the corresponding sequent of linear logic. But linear logic cannot naturally represent timed Petri nets which are extensions of ordinary Petri nets with respect to time concept. So we extend linear logic with respect to time concept in order to introduce a resource-conscious and time-dependent logical system, that is, temporal linear logic. This system has some temporal operators "" which means a resource usable only once at the next time, "" which means a resource usable only once at anytime, and a modal storage operator "!" which means a resource usable any times at anytime. We can show that the reachability problem for timed Petri nets is equivalent to the provability for the corresponding sequent of temporal linear logic. In this paper, we also represent the description of synchronous communication model by temporal linear logic. The expressive power of temporal linear logic will be applicable to various fields of computer science.

To estimate moving object velocity in an image sequence is useful for a variety of applications, such as velocity measurement, computer vision and monitoring systems. An effective way is to approach it in the transform/spatiotemporal mixed domain (MixeD), which transforms the 3-D signal processing problem into 1-D complex signal processing. But it remains a problem how to select several spatial frequency points in the MixeD which may influence the accuracy of velocity estimation and object detection. In this paper, a spatial frequency selection method has been proposed, which can choose the appropriate spatial frequency points out of a number of points in MixeD automatically. So the velocity estimation problem can be addressed by solving the coupled equations established over two selected appropriate points in 2-D spatial frequency domain other than searching for the spectral energy plane over a number of points selected by experience. In this method, evaluation functions corresponding to image sequence with one moving object and two moving objects are established firstly, and the selection is then achieved by using the established evaluation functions together with a threshold. The simulation results show that the proposed method is effective on the appropriate spatial frequency selection.

This letter proposes a new detection method of human faces in gray scale image with cluttered background using a face template and elliptical structure of the human face. This proposed method can be applicable even in the cases that the face is much smaller than image size and several faces exist in one image, which is impossible in the existing one.

The expected lengths of the parsed segments obtained by applying Lempel-Ziv incremental parsing algorithm for i.i.d. source satisfy simple recurrence relations. By extracting a combinatorial essence from the previous proof, we obtain a simpler derivation.

The a-Si TFT characteristics were studied for process temperatures of as low as 100C. The a-Si TFT kept normal characteristics for process temperature of as low as 150C. The a-Si TFT bias temperature stability was evaluated and degradation of stability initiated at around 150C. The characteristics of a-Si TFT fabricated on plastic substrates were the same as those of a-Si TFT fabricated on glass substrates at low process temperature. TFT-LCD fabricated at a process temperature lower than the glass transition temperature of plastic substrates indicated good display image. These results indicate the possibility of fabricating TFT-LCD on plastic substrates, which would promote the application of a-Si TFT-LCD for mobile devices.

In this work, a temperature stable voltage-to-frequency converter (VFC) in which the output frequency is proportional to the input voltage is proposed. The output frequency range is from 22 kHz to 60 kHz and the difference between simulated and calculated values is less than about 5% for this range of output frequency. The temperature variation of sample output frequencies is less than 0.5% in the temperature range -25C to 75C.

Conventional metal-glazed thick-film resistors are applied to Hybrid Integrated Circuits, chip resistors and others. These resistors are usually fired at a high temperature of around 850C on ceramic substrates. Recently, however, attempts have been made to fire some metal-glazed thick-film resistors at lower temperatures on glass substrates for application as the control resistors for the discharge current of dc Plasma Display Panels (PDPs). We have attempted to realize such low-firing-temperature thick-film resistors using Pb2Ru2O7-x as conductive particles, two kinds of lead-borosilicate glasses as binders, and three kinds of metallic oxide as additives, which are fired at 580C on a soda lime glass substrate. The electrical properties of the specimens, 16 kinds in all, fabricated from various combinations of binder glasses, additives and electrode materials have been measured. Effective dimensions of the specimen resistor are 0.25 0.25 mm2 or less in surface area, since extremely small size is required by PDPs. The effect of the combination of additive and binder glass on the conductive particles of Pb2Ru2O7-x has been examined in detail, together with the affinity for electrical conjunction between resistor and electrode.

We propose a variation of the Context Tree Weighting algorithm for tree source modified such that the growth of the context resembles Lempel-Ziv parsing. We analyze this algorithm, give a concise upper bound to the individual redundancy for any tree source, and prove the asymptotic optimality of the data compression rate for any stationary and ergodic source.

Shared memory multiprocessors are frequently used as compute servers with multiple parallel programs executing at the same time. In such environments, an operating system switches the contexts of multiple processes. When the operating system switches contexts, in addition to the cost of saving the context of the process being swapped out and that of bringing in the context of the new process to be run, the cache performance of processors also can be affected. The blocked algorithm improves cache performance by increasing the locality of memory references. In a blocked program using this algorithm, program performance can be significantly affected by the reuse of a block loaded into a cache memory. If frequent context switching replaces the block before it is completely reused, the cache locality in a blocked program cannot be successfully exploited. To address this problem, we propose a preemption-safe policy to utilize the cache locality of blocked programs in a multiprogrammed system. The proposed policy delays context switching until a block is fully reused within a program, but also compensates for the monopolized processor time on processor scheduling mechanisms. Our simulation results show that in a situation where blocked programs are run on multiprogrammed shared-memory multiprocessors, the proposed policy improves the performance of these programs due to a decrease in cache misses. In such situations, it also has a beneficial impact on the overall system performance due to the enhanced processor utilization.

In this paper, the distributions of two spectral intensities along the axis of an arc column of the breaking arc are measured by using a combination of a CCD color camera and an additional filter, and arc temperature and metal-vapor quantity are calculated, when copper electrodes interrupt circuits of dc 50 V/3.3 A and 5.0 A. As results; The spectral intensities of excited copper atoms are the strongest near the cathode and become weaker with distance from the cathode in the small number of breaking arcs. The spectral intensities become strong near the anode in the large number of breaking arcs. The average arc temperature in the cross-section of an arc column is high near both the cathode and the anode, and the temperature distribution in the cross-section of the arc column is high at the axis of the arc column, and the arc temperature along the axis of the arc column is high near both the cathode and the anode. The metal-vapor quantity is low near both the cathode and the anode, and it is much at the center of the arc column.

A Rayleigh lidar (laser radar) system was developed and is now working well for temperature observations of the middle atmosphere at Poker Flat Research Range near Fairbanks, Alaska (65.1 N, 147.5 W). A comparison of lidar data and balloon sonde data showed good agreement in overlapped altitudes. The atmospheric fluctuations are detected in the temperature profiles obtained by the Rayleigh lidar and these are useful for the study of gravity waves. A Rayleigh Doppler lidar for wind measurements of the middle atmosphere is under the phase of development. The expected accuracy in measurements of horizontal winds up to an altitude of 60 km is smaller than 6 m/s in 2 hours observation. The system will be operated at Poker Flat after the completion of development. The combination of these lidars and radars installed at Poker Flat, give us chances of simultaneous observations of the structure and dynamics of the atmosphere in broad range of altitudes. Here, we give descriptions of the Rayleigh lidar and the Rayleigh Doppler lidar for the observations of the Arctic middle atmosphere at Poker Flat.

When a mobile station with a call in progress moves across cell boundary in a cellular mobile communications system, the system must switch the circuit to the base station in the destination cell to enable uninterrupted communications in a process called "handoff. " However, if a circuit to the destination base station cannot be secured when a handoff is attempted, the call is forcibly terminated. Studies have therefore been performed on methods of decreasing the percentage of forcibly terminated calls by giving handoff calls priority. With the aim of simplifying system design, we propose a system for automatically setting the number of circuits reserved for handoff based on the handoff block rate. In this paper, we describe this system and evaluate static traffic characteristics taking into account reattempt calls, the occurrence of which can have a major effect on system performance. We also consider the effects of the proposed system on service quality since giving priority to handoff calls and decreasing the rate of forced terminations results in a tradeoff with the blocking rate of new call attempts. Finally, we evaluate the traffic characteristics associated with the number of control requests, an important element in estimating the processing capacity required by control equipment at the time of system design.