A Universal Performance Chart for CPU Cooling Devices

This article deals with performance evaluation of the discrete ordinates method in terms of its capacity to provide accurate results in solving radiation mode problems with different complexities. The problem formulation is done keeping in view the heat transfer process in an evaporator used in a coal-based thermal power station. The hot gas mass in the evaporator is assumed to be a heat source with two different shapes, spherical and conical. The evaporator walls that are covered with a water cooling jacket are modeled with a convective boundary condition. The gas is assumed to be gray and absorbing–emitting. The solution of the radiative transport equation is carried out using the discrete ordinates method. Parametric studies are performed for a wide range of aspect ratio, extinction coefficient, and convective heat transfer coefficient. The code is validated by comparing the result of discrete ordinates method with the exact and the discrete transfer method for nonradiative as well as radiative equilibrium conditions.     

Thermal evaluation of vertical greenery systems for building walls

This research involves the study of 8 different vertical greenery systems (VGSs) installed in HortPark to evaluate the thermal impacts on the performance of buildings and their immediate environment based on the surface and ambient temperatures. VGSs 3 and 4 have the best cooling efficiency according to the maximum temperature reduction of the wall and substrate surfaces. These results point to the potential thermal benefits of vertical greenery systems in reducing the surface temperature of buildings facades in the tropical climate, leading to a reduction in the cooling load and energy cost. In terms of the lowest diurnal range of average wall surface temperature fluctuation, VGSs 4 and 1 show the highest capacities. No vertical greenery system performs well in term of the diurnal range of average substrate temperature fluctuation. By limiting the diurnal fluctuation of wall surface temperatures, the lifespan of building facades is prolonged, slowing down wear and tear as well as savings in maintenance cost and the replacement of façade parts. The effects of vertical greenery systems on ambient temperature are found to depend on specific vertical greenery systems. VGS 2 has hardly any effect on the ambient temperature while the effects of VGS 4 are felt as far as 0.60 m away. Given the preponderance of wall facades in the built environment, the use of vertical greenery systems to cool the ambient temperature in building canyons is promising. Furthermore, air intakes of air-conditioning at a cooler ambient temperature translate into saving in energy cooling load.     

Characterization of MEMS Devices for the Study of?Superfluid Helium Films

Measurements on the mechanical properties of MEMS resonators were performed to characterize such devices at room temperature and low temperatures. Using state-of-the-art silicon integrated circuit technology, we have designed, fabricated, and manufactured resonators consisting of a pair of parallel plates with a well-defined gap whose size can be controlled with a high accuracy down to the sub-micron range. A full study of resonance properties at various pressures was performed at room temperature. We will discuss the details of design, fabrication, and operation. These studies open up a window of opportunities to look for novel phenomena in quantum fluids such as in superfluid ³He films.     

Beneficial effects of nocturnal hemodialysis in a hemodynamically unstable patient with AL‐amyloidosis

We present a patient with primary systemic AL‐amyloidosis, who stabilized hemodynamically on nocturnal hemodialysis (NHD). The NHD allowed a significant reduction in ultrafiltration rates which likely underlies the procedural tolerability. It also provided an increase in urea clearance, better control of serum phosphorus levels without the use of any binders, and normalization of blood pressure despite the discontinuation of all antihypertensive agents. Given the autonomic derangements associated with AL‐amyloidosis pathophysiology and the clinical benefits of NHD on hemodynamic stability, the use of intensive hemodialysis may be considered for the management of patients with unstable hemodynamic profiles.     

Defect cluster recognition system for fabricated semiconductor wafers

The International Technology Roadmap for Semiconductors (ITRS) identifies production test data as an essential element in improving design and technology in the manufacturing process feedback loop. One of the observations made from the high-volume production test data is that dies that fail due to a systematic failure have a tendency to form certain unique patterns that manifest as defect clusters at the wafer level. Identifying and categorising such clusters is a crucial step towards manufacturing yield improvement and implementation of real-time statistical process control. Addressing the semiconductor industry’s needs, this research proposes an automatic defect cluster recognition system for semiconductor wafers that achieves up to 95% accuracy (depending on the product type).     

Development of pseudo-ductile permanent formwork for durable concrete structures

The present investigation focuses on a new approach for the construction of durable concrete structures. Using Pseudo-ductile Cementitious Composites (PDCC) of relatively low water/binder ratio, permanent formworks are first fabricated. Normal concrete is then cast to make structural components. With low permeability and high crack resistance, the permanent formwork acts as effective surface cover to prevent the corrosion of steel reinforcements. The formwork can be made with PDCC alone, or with the incorporation of Glass Fiber Reinforced Plastics (GFRP) rods. In some structural components, the GFRP reinforcements will be sufficient to provide the necessary load-carrying capacity. When higher loads are to be carried, steel reinforcements can be added to produce a component with very high durability (due to the thick cover to steel) as well as ductile behavior. This paper focuses on mechanical aspects of this construction concept. The development of PDCC for formwork fabrication is first described. The bond between PDCC and concrete, in relation to various surface treatment methods, will be investigated with beam specimens. Test results on concrete beams made with GFRP reinforced PDCC formwork are then presented and compared to theoretical predictions. A design example is performed to demonstrate the use of GFRP/PDCC permanent formwork for constructing the deck of a footbridge. The results of this investigation show promise of the technology for practical applications.     

Study of residence time distribution and mill hold-up for a continuous centrifugal mill with various G/D ratios in a dry-grinding environment

It is important to determine the residence time distribution (RTD) of a mill in order to predict the performance of the mill. In this study, the residence time distribution of a continuous centrifugal mill was measured experimentally by using aluminum powder as a tracer in a dry-grinding environment. Aluminum powder was placed into the continuous centrifugal mill chamber as a pulse under a steady-state condition, and then, the discharge time and proportional concentration of the tracer was measured using a metal detector at various G/D ratios and feed rates. During the measurement procedure, the mill product was collected and analyzed with regard to the size distribution to investigate the relationship between the mill product and the characteristics of RTD. In addition, the mill hold-up data was also analyzed after measurement. These test results can be used to predict the mill product size distribution in combination with a kinetic grinding model.     

Performance Analysis of Split-Winding Doubly Salient Permanent Magnet Motor for Wide Speed Operation

In this paper, various flux-weakening techniques available for wide speed operation of the doubly salient permanent magnet (DSPM) motor are reviewed. A new split-winding topology capable of widening the speed range is proposed, which is valid not only for the DSPM motor with stationary PMs, but also for that with rotary PMs. Based on the parameters obtained by finite element analysis, the performance of the proposed DSPM motor is analyzed. The results show that this motor combines the features of wide speed range, high efficiency, simple structure, and low cost.     

Slow diffusion of LPG vehicles in China—Lessons from Shanghai,Guangzhou and Hong Kong

Compared with other alternative fuel vehicles (AFV), LPG vehicles (LPGV) have lower economic and technological barriers, leading to its faster growth in some developing countries in recent years. By means of regulation, Shanghai managed to have nearly all taxis converted to LPGV in the early 2000s, and all taxis and 80% of buses in Guangzhou are LPGV. Nevertheless, LPGV diffusion in China (excluding Hong Kong) has been slow and even showing signs of retreating. By 2008, less than 5% of taxis in Shanghai were LPGV. This paper looks into the problem by comparing the LPGV development of Shanghai, Guangzhou versus that of Hong Kong where the LPGV development seems to be running well. The obstacles of LPGV development in China include a lack of policy coherence between the central and local governments; insufficient price advantage of Autogas; not enough fueling stations; and high maintenance costs due to immature technology and poor quality control. Bi-fuel system has further magnified the problems in China. In order to facilitate the use of alternative fuel, efforts should be made to increase the number of AFVs as well as to ensure the availability and price-competitiveness of the alternative fuel concerned.