有阀型小孔脉管制冷机的深入研究

为了克服第三代脉管制冷机存在的制冷温度不稳定的缺陷,本文从提高脉管制冷效率,进一步降低制冷温度的角度,对有阀型小孔脉管制冷机进行了研究。通过理论计算和实验改进,有阀型单级脉管制冷机取得了３４Ｋ的无负荷制冷温度,在８０Ｋ获得３０Ｗ以上的制冷功率,其制冷效率达到国外同类商品型有阀脉管制冷机的水平。     

Synthesis and Sensitivity of Hexanitrohexaaza-isowurtzitane(HNIW)

Hexanitrohexaaza-isowurtzitane(AC-HNIW) was synthesized by using a precursor invented by Asahi. The purity, which was measured by high performance liquid chromatography(HPLC), was determined to be 99.2%. From the results, it is expected that the propellants or explosives composed of AC-HNIW indicated higher performance in specific impulse, ballistics and detonation velocity. The structure of AC-HNIW was identified by IR and NMR. The results indicated that AC-HNIW had the same structure as CL-20 which was produced by Thiokol corporation. The sensitivity and thermal decomposition properties of AC-HNIW were also measured in order to elucidate HNIW performance. The results were compared with CL-20. The sensitivity of AC-HNIW was determined to be the same as CL-20.     

Entropic analysis of adsorption open cycles for air conditioning. Part 2: interpretation of experimental data

The full second‐law analysis, developed in Part 1 (M. Pons and A. Kodama, Int. J. Energy Res. 2000; 24 : 251–262) is applied to experimental results. That approach takes into account the irreversibilities due to the open character of the cycle. Measurements are performed on a solid desiccant cooling unit operated in the ventilation mode. Experimental data permit us to establish the entropy balance of the unit. The results show that the sum of all the considered entropy productions completely explain the difference between the Carnot COP and the actual COP of the unit. The effects of three experimental parameters are investigated: the rotation speed of the dehumidifier (desiccant wheel), the air velocity and the regeneration temperature. Experimental results show that there exists an optimal rotation speed which results from a combination between the different entropy productions in the cycle. When the air velocity is increased, together with an accordingly optimized rotation speed, the cooling capacity increases while the COP decreases due to increases in the entropy productions in the dehumidifier and sensible heat exchanger. Moreover, it appears that the most significant entropy productions take place in the dehumidifier and heating system. In the investigated experimental unit, these two entropy productions have similar magnitudes. However, when the regeneration temperature is increased, the irreversibilities due to mass exchanges with outside air become comparable to these and surely should not be forgotten in a global optimization of the process. The present analysis is a solid basis for reducing the largest entropy productions thus optimizing the process. Copyright © 2000 John Wiley & Sons, Ltd.     

Entropic analysis of adsorption open cycles for air conditioning. Part 1: first and second law analyses

Rotary desiccant units for air‐conditioning and ventilation use the principle of adsorption open cycles. In this study, a thermodynamic analysis is first developed that emphasises the open character of the cycle, and especially the consumption of liquid water. Then, the system is ‘closed’ with the help of virtual open systems that exchange mass flows with the cooling unit and only heat fluxes with heat sources. The entropic analysis is developed, first for these virtual systems showing that they are irreversible, second for each component of the unit where heat losses are taken into account. The equations are derived in such a manner that the different irreversibilities can directly be compared. In addition, the concept of entropic mean temperature is introduced and applied to the two virtual systems because it is very helpful for representing the variations of the entropy productions in these systems. In Part 2, these analyses will be applied to experimental data showing that they bring lots of information. Copyright © 2000 John Wiley & Sons, Ltd.     

Synthesis and properties of phospholipid polyurethanes with poly(isoprene) soft segment

Polyrethanes, based on 2-[bis(2-hydroxyethyl)methylammoni]ethylstearylphosphate, alone or together with 1,4-butanediol as the chain extender, poly(isoprene) diol and 4,4′-methylenediphenyl diisocyanate, were prepared. These segmented phospholipid polyurethanes were characterized by IR, elemental analyses, and gel permeation chromatography. The polyurethane, with both phospholipid diol and 1,4-butanediol as the chain extender, was further investigated by differential scanning calorimetry, x-ray diffraction, scanning electron microscopy, plasma contact and clotting time. An x-ray diffraction measurement for the polymer shows a intense scattering at 79.3 Å corresponding to the length of soft segments, which is hydrophobic poly(isoprene), and a weak diffuse scattering at 5.1 Å corresponding to the distance between the hydrophobic poly (isoprene) layers. The hemocompatibilities of the polymer were evaluated by platelet rich plasma contacting studies and by scanning electron microscopy using medical grade poly(vinyl chloride) as control. The hot-pressed films of the polymer exhibit a favorable surface in terms of platelet adhesion, and the morphology of adhered platelets undergoes to a relatively lower degree of variation compared to poly(vinyl chloride). Moreover, the clotting time of the polymer in contact with human platelet rich plasma was 220, 100, and 86 s for the phospholipid-based polyurethane, poly(vinyl chloride), and glass, respectively. © 1996 John Wiley & Sons, Inc.     

Impact of Narrowing Density of States in Semiconducting Polymers on Performance of Organic Field-Effect Transistors

To improve the performance of organic field-effect transistors (OFETs) employing π-conjugated polymers, a basic understanding of the relationships between the material properties and device characteristics is crucial. Although the density of states (DOS) distribution is one of the essential material properties of semiconducting polymers, insights into how the DOS shape affects the mobility (µ), subthreshold swing (S), and contact resistance (R_C) in OFETs remain lacking. In this study, by combining sensitive DOS measurements and multilayered OFET structures, it is experimentally demonstrated that narrower DOS widths in the polymer channels lead to higher µ, smaller S, and lower R_C. By contrast, variation of the DOS in the bulk layer does not affect the performance. These results demonstrate a direct relationship between the polymer properties and OFET performance and highlight the importance of controlling the DOS width in π-conjugated polymers.