Results 1 - 10 of 9639
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[en] Thermoforming is one of the most versatile and economical processes available for polymer products, but cycle time and production cost must be continuously reduced in order to improve the competitive power of products. In this study, water spray cooling was simulated to apply to a cooling system instead of compressed air cooling in order to shorten the cycle time and reduce the cost of compressed air used in the cooling process. At first, cooling time using compressed air was predicted in order to check the state of mass production. In the following step, the ratio of removed energy by air cooling or water spray cooling among the total removed energy was found by using 1-D analysis code of the cooling system under the condition of checking the possibility of conversion from 2-D to 1-D problem. The analysis results using water spray cooling show that cycle time can be reduced because of high cooling efficiency of water spray, and cost of production caused by using compressed air can be reduced by decreasing the amount of the used compressed air. The 1-D analysis code can be widely used in the design of a thermoforming cooling system, and parameters of the thermoforming process can be modified based on the recommended data suitable for a cooling system of thermoforming
[en] In the continuous effort to improve antiproton stacking rate, a new type of equalizers has been developed and installed in antiproton accumulator. The R and D of these new equalizers is described in this paper. Equalizers are used in Fermilab antiproton stochastic cooling to compensate frequency response of the cooling system. Usually both amplitude and phase compensations are needed. However in most cases it is difficult to achieve a satisfactory compensation for both because of their interdependence. To make it more difficult is that in some cases large compensations (10 to 20 db of amplitude compensation or more than 100 degree of phase compensation) are needed near the low or high ends of a frequency band. Recently a new compensation scheme of equalizers is proposed for Fermilab antiproton accumulator. This scheme originated from the requirement to maximize the system performance resulting in a request for the phase of the cooling system transfer function to be extremely flat. For this kind of phase correction, a new type of equalizers has been developed
[en] Cooling of hadron beams (including heavy-ions) is a powerful technique by which accelerator facilities around the world achieve the necessary beam brightness for their physics research. In this paper, we will give an overview of the latest developments in hadron beam cooling, for which high energy electron cooling at Fermilab's Recycler ring and bunched beam stochastic cooling at Brookhaven National Laboratory's RHIC facility represent two recent major accomplishments. Novel ideas in the field will also be introduced
[en] Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.
[en] Nocturnal cooling can work under clear sky condition of the humid tropical climate. Such effect had been observed in a cool storage facilities for potatoes and for temporary storage of fresh vegetables installed in highland area of Candi kuning village of Bali. Test results have shown that the rate of heat dissipation to the sky could reduce storage temperature to 15 oC had been achieved when the nocturnal cooling unit was combined with modified cooling tower and 1 kW cooling effect of an auxiliary cooling unit. Under such condition the facility could maintain better quality of stored vegetables, such as broccoli, shallot, and celery as compared to those stored in room without cooling facility. The estimated average cooling rate due to night sky radiation was 47.6 W/m2, on September 28, 1999 and 47.2 W/m2 with the lowest water temperature of 14 oC under ambient temperature of 16 oC
[en] The KSTAR cooling water system (CWS) consists of a primary cooling water system (PCWS), a secondary cooling water system (SCWS), and a de-mineralizing and de-ionized water system (DIWS). The PCWS cooling loops have been made for the poloidal field (PF) and toroidal field (TF) magnet power supplies (MPS), vacuum vessel (VV), electron cyclotron heating (ECH), ion cyclotron heating (ICRH), vacuum pumps, diagnostics, helium facility, etc. The CWS had been done individual commissioning of each system to confirm the design specifications by the end of 2006 and had gradually begun operation for the KSTAR ancillary devices by March 2008
[en] Electron cooling in the Fermilab Recycler ring is found to create correlation between longitudinal and transverse tails of the antiproton distribution. By separating the core of the beam from the tail and cooling the tail using 'gated' stochastic cooling while applying electron cooling on the entire beam, one may be able to significantly increase the overall cooling rate. In this paper, we describe the procedure and first experimental results
[en] In Korea, design concepts of sodium-cooled fast reactors (SFRs) have been developed since 1997 by the Korea Atomic Energy Research Institute (KAERI). The 255th Atomic Energy Commission of Korea, held in Dec. of 2008, determined a long-term research and development plan for future nuclear systems including the SFR. According to the plan, it is scheduled to submit an application for licensing of an SFR demonstration reactor in 2017. In order to prepare the licensing of the demonstration reactor, the general design requirements (GDRs) for the SFR should be established because they are used as rules in the safety evaluation of the design for the licensing by the regulatory body. The current GDRs were developed based on the design of the LWR and enacted as the articles 12 to 49, including the article 2, in the 'Regulations on Technical Standards for Nuclear Reactor Facilities, Etc' (hereafter referred to as 'regulations on technical standards'), which is the Ordinance No. 1 of the Ministry of Education, Science, and Technology. In this paper, the applicability of the current GDRs for the LWR to the design of the SFR was evaluated as a part of activities to develop the GDRs for the SFR
[en] This paper presents a GPC-PID control strategy for a cooling-coil unit in heating, ventilation and air conditioning systems. By analysis of the cooling towers and chillers, different models in the occupied period are considered in each operating condition. Because of the complication of components, well tuned PID controllers are unsatisfied, and the results are poor over a wide range of operation conditions. To solve this problem, a GPC-PID controller with hierarchical structure is proposed based on minimizing the generalized predictive control criterion to tune conventional PID controller parameters. Simulation and experiments show that the proposed controller is able to deal with a wide range of operating conditions and to achieve better performance than conventional methods
[en] Complete text of publication follows. Models for the thermoremanent magnetisation (TRM) acquisition of single-domain (SD) magnetic grains, include a time parameter (t), that defines the behaviour of an assemblage of magnetic grains for a given temperature in time t. This time t directly controls the blocking temperature and the intensity of the recorded TRM. However, in a cooling system, e.g., a lava, the temperature is constantly changing, making t ∼ 0 s for any given temperature. In the geophysical literature, previous studies looking at the effect of cooling rate on TRM acquisition [e.g., Dodson and McClelland-Brown, 1980; Halgedahl, et al., 1980] have circumnavigated this problem by taking discrete time intervals, i.e., steps with an equivalent time teq determined by the cooling rate. By numerically solving the master equation [Spinu, et al., 2001], it is possible to directly relate teq to ∂T/∂t without any need to use the step approximation. I investigate the effect of using the more robust definition of teq, and the implications for TRM acquisition and palaeointensity determination. For ∂T/∂t I have employed the standard Newtonian cooling rate equation.