Chip Multiprocessors (CMPs) have been prevailing in the modern microprocessor market. As the significant heat is converted by the ever-increasing power density and current leakage, the raised operating temperature in a chip has already threatened the system?s reliability and led the thermal control to be one of the most important issues needed to be addressed immediately in chip designs. Due to the cost and complexity of designing thermal packaging, many Dynamic Thermal Management (DTM) schemes have been widely adopted in modern processors. In this study, we focus on developing a simple and accurate thermal model, which provides a scheduling decision for running tasks. And we show how to design an efficient DTM scheme with negligible performance overhead. First, we propose an efficient DTM scheme for multimedia applications that tackles the thermal control problem in a unified manner. A DTM scheme for multimedia applications makes soft realtime scheduling decisions based on statistical characteristics of multimedia applications. Specifically, we model application execution characteristics as the probability distribution of the number of cycles required to decode frames. Our DTM scheme for multimedia applications has been implemented on Linux in two mobile processors providing variable clock frequencies in an Intel Pentium-M processor and an Intel Atom processor. In order to evaluate the performance of the proposed DTM scheme, we exploit two major codecs, MPEG-4 and H.264/AVC based on various frame resolutions. Our results show that our DTM scheme for multimedia applications lowers the overall temperature by 4 degrees C and the peak temperature by 6 degrees C (up to 10 degrees C), while maintaining frame drop ratio under 5% compared to existing DTM schemes for multimedia applications. Second, we propose a lightweight online workload estimation using the cumulative distribution function and architectural information via Performance Monitoring Counters (PMC) to observe the processes dynamic workload behaviors. We also present an accurate thermal model for CMP architectures to analyze the thermal correlation effects by profiling the thermal impacts from neighboring cores under the specific workload. Hence, according to the estimated workload characteristics and thermal correlation effects, we can estimate the future temperature of each core more accurately. We implement a DTM scheme considering workload characteristics and thermal correlation effects on real machines, an Intel Quad-Core Q6600 system and Dell PowerEdge 2950 (dual Intel Xeon E5310 Quad-Core) system, running applications ranging from multimedia applications to several benchmarks. Experiments results show that our DTM scheme reduces the peak temperature by 8% with 0.54% performance overhead compared to Linux Standard Scheduler, while existing DTM schemes reduce peak temperature by 4% with up to 50% performance overhead.

The design and implementation of a dynamic voltage restorer (DVR) is presented in this thesis. The proposed DVR can restore the end-user voltage to its normal level by rapidly injecting a compensating voltage onto the power line against the upstream power disturbances. The control algorithm uses the concept of reference voltage tracking method. Based on the electric circuit theory, the filter of the DVR is also analyzed. Besides, performance of the proposed method is simulated and compared with other different control methods by using Matlab-simulink/PSB. The results show the effectiveness of the proposed method. A 2.18 KVA DVR prototype is implemented to verify the performance of the proposed method.

The induced phenomena caused by rolling or sliding action of a nano-particle on the work were considered in this study. The analysis was done by the molecular dynamics method.The effects on the removals of work, the roughness induced by nano-particle and the thickness of the damage layer caused by the depth of indentation, the shape of particle and the adhesive strength btween the particle and the work will also be discussed. The result shows that the particle in rolling process removed atoms easier than in sliding process. The removals of work in the process of rolling depend on the adhesive strength between the nano-particle and the work. More powerful of the adhesive strength will increase the amount of removal. But, the adhesive strength was not the only factor in the process of sliding. The rake angle between the nano-particle and the work was the important factor, too. In order to remove the atoms during sliding process, not only the adhesive strength must be strong enough but also the rake angle must be small enough. The increase of the strength between the particle in the shape of ball and the work will cause more amorphous atoms in both rolling and sliding process. The thickness of the damage layer of the work surface was also affected by the rake angle. But the roughness was little affected by the adhesive strength between the nano-particle and the work.

In this thesis, the dynamic responses of harmonic drive (H.D.) systems under different operating conditions are investigated. The numerical simulation and the experimental measurements of harmonic drive systems are included in this thesis. The effects of flexspline of harmonic drive, i.e., the torsional stiffness and the damping ratio on the response of corresponding system are studied .Lagrange¡¦s equation is employed to derive the equation of motion of the system. The system equation with a nonlinear torsional stiffness is solved by using the 6th order Runge-Kutta method. Comparison between numerical simulation results and experimental measured data indicate that the proposed harmonic drive model is accurate and feasible for simulating the dynamic response of a harmonic drive system.

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A Study of Dynamic Resource on IC Design Industry

Abstract The harmonic drive mechanism has been used wildly in industrial robots. High reduction ratio, few components, and quiet torque transfer are the advantages of this device. In this thesis, the dynamic characteristic of an integrated DC motor and harmonic driver system is investigated. The dynamic equations of the harmonic drive systems are derived by applying Lagrange¡¦s equation. Two different harmonic driver designs, i.e. a cup-type with two teeth difference and a circular type with four teeth difference are used in the analysis. The system responses are simulated by employing the sixth order Runge-Kutta method. Comparison between numerical simulation results and experimental results, it indicates that the proposed model is feasible and accurate for simulating the dynamic response of an electro-mechanical integrated harmonic drive system.

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This paper extends the real options literature by discussing an investment problem, where a firm has to determine optimal investment timing and optimal capacity choice at the same time under conditions of irreversible investment expenditures and uncertainty in future demand. After the project is installed with a certain maximum capacity, this capacity is fixed as an upper boundary to the output and cannot be adjusted later on. It turns out that, in the framework of this once and for all decision, uncertainty in future demand leads to an increase in optimal installed capacity. But on the other hand it causes investment to be delayed to an extent that even small uncertainty makes waiting and accumulation of further information the optimal decision for large ranges of demand. Limiting the capacity which may be installed weakens this extreme effect of uncertainty. (author's abstract) / Series: Report Series SFB "Adaptive Information Systems and Modelling in Economics and Management Science"

This study was designed to examine the effect of impact velocity on the crushing behavior of open-cell aluminum foam over a range of velocities similar to what would be encountered for impact mitigation and blast protection applications. An experimental set-up was designed, fabricated and validated for studying the crushing response of cellular materials at high velocities. It consists of a gas gun, a pressure bar, high-speed data acquisition and high-speed imaging. The facility uses high-speed video images of the crushing event synchronized to force measurements with a pressure bar at one end of the foam to examine the dynamic stress and deformation history of foam specimens. Ten pores per inch open-cell Al-6101-T6 Doucel foam cylindrical specimens with a relative density of about 0.085 were impacted in the rise direction at velocities ranging from 21.6 to 127 m/s. The experimental results show that for impact speeds greater than about 40 m/s crushing of the foam occurred through a shock front. Furthermore, the experiments show an increase in the densification strain, average stress in the crushed region and shock velocity with increasing impact velocity, whereas the stress in the uncrushed region appears to be insensitive to velocity. A method of determining the states across a shock front was derived from shock equations by enforcing conservation of mass and momentum. This was verified through a combination of experiments and direct measurements. The use of high-speed imaging and pressure bar measurements allowed this derivation to be independent of any constitutive model and showed that the assumptions in the commonly used rigid-perfectly-plastic-locking model are not applicable for dynamic impacts. A shock Hugoniot was generated from the test data to characterize the impact response of the foam. / text