An analysis of stochastic properties of room temperature, cooling load and air-conditioning systems

Exact prediction of the heating and cooling load, proper sizing of the HVAC systems and the optimal control of the HVAC systems are essential to minimize energy consumption. Since external climates which are the main factors affecting cooling loads fluctuate randomly, calculation of the cooling load must take account of the stochastic nature of these processes.

This paper proposes methods of thermal calculation which give the density function of the HVAC system load considering the stochastic properties of the external climates. Simple HVAC systems are analysed for illustration of the applicability of these methods to many practical problems.     

Simulation of water-bloom in a eutrophic lake—I. Photosynthetic characteristics of Microsystis aeruginosa

A perspective of how to simulate “emergence and/or disappearance of the water-bloom… dense population of a blue-green alga, Microcystis aeruginosa at the surface of eutrophic waters… ” was presented.The algal photosynthetic activity. Q_o2 as a function of irradiation light intensity. I, could be represented by the Blackman model, taking the algal content. C of chlorophyll-α and water temperature. 0 as parameters.When the cells that had been cultured under dim light were transferred to a new environment, wherein the light intensity was from 0 (dark) to the level much brighter than the dim light, the value of C exhibited various responses against time. Subtracting the rate of chlorophyll-α degradation from that of chlorophyll-α synthesis, the rate of change in C values during the light-adaptation period was studied.     

Effect of copper and hexavalent chromium on the specific growth rate of ciliata isolated from activated-sludge

After growing mass and monoxenic cultures of three species of Ciliata (Vorticella microstoma, Colpidium campylum, and Opercularia sp.) with Alcaligenes faecalis as the sole protozoan food, and confirming that copper and hexavalent chromium did not affect the bacterial growth, the effect of these metals on the specific growth rate of each protozoa was examined. The term IL_m (median inhibitory limit) was used to define the metal concentration required to reduce the specific growth rate of protozoa to one-half of that of a control. The IL_m for copper was: 0·25 mg 1⁻¹ (V. microstoma), 0·32 mg 1⁻¹ (C. campylum), and 0·27 mg 1⁻¹ (Opercularia sp.). Regarding hexavalent chromium, IL_m for V. microstoma, C. campylum, and Opercularia sp. were 0·53, 12·9 and 20·2 mg 1⁻¹, respectively. Acclimation of each protozoa to these metals for 96 h resulted in IL_m enhanced values of 1·2–2·2 times as large as that for the control.     

Ellipsometric determination of optical properties of carbazole-containing poly(l-glutamate) thin films prepared from different solvents

In this study, the refractive indices (n) and thicknesses of carbazole-containing hole-transport materials such as poly(γ-carbazolylethyl l-glutamate) (PCELG) and poly(N-vinyl carbazole) (PVCz) films were determined by carrying out ellipsometric measurements. The thicknesses of PCELG and PVCz films determined by ellipsometric analysis were in good agreement with those determined by surface profilometry. The dependence of the refractive indices of the PCELG films on film thickness was classified into two types on the basis of the solvent from which the films were prepared: the refractive indices either increased with increasing film thickness, as in the case of PCELG films prepared from 1,2-dichloroethane (DCE) and monochlorobenzene (?-Cl), or were independent of the film thickness, as in the case of films prepared from 1,1,2,2-tetrachloroethane (TCE). A comparison of these results with the structures of the polymers, as determined by ¹H NMR, reveals that the two types of dependences of the refractive indices of the PCELG thin film on the film thickness can be attributed to the two types of aggregation structures and/or orientational characteristics corresponding to the helical conformation of the polymer. In contrast, the refractive indices of PVCz films are governed mainly by the film thickness. Finally, we would like to emphasize that the combination of ellipsometry and other techniques such as NMR and surface profilometry provide information not only on the film thickness and refractive index but also on the aggregation structure in thin films with thicknesses on the order of 50 nm.     

Radiocarbon (14C) diurnal variations in fine particles at sites downwind from Tokyo, Japan in summer

The radiocarbon ((14)C) of total carbon (TC) in atmospheric fine particles was measured at 6 h or 12 h intervals at two sites, 50 and 100 km downwind from Tokyo, Japan (Kisai and Maebashi) in summer 2007. The percent modern carbon (pMC) showed clear diurnal variations with minimums in the daytime. The mean pMC values at Maebashi were 28 ± 7 in the daytime and 45 ± 16 at night (37 ± 15 for the overall period). Those at Kisai were 26 ± 9 in the daytime and 44 ± 8 at night (37 ± 12 for the overall period). This data indicates that fossil sources were major contributors to the daytime TC, while fossil and modern sources had comparable contributions to nighttime TC in the suburban areas. At both sites, the concentration of fossil carbon as well as O(3) and the estimated secondary organic carbon increased in the daytime. These results suggest that fossil sources around Tokyo contributed significantly to the high daytime concentration of secondary organic aerosols (SOA) at the two suburban sites. A comparison of pMC and the ratio of elemental carbon/TC from our particulate samples with those from three end-member sources corroborates the dominant role of fossil SOA in the daytime.     

Effect of the Chevron Angle on Cooling Heat Transfer Characteristics of Supercritical Pressure Fluids in Plate Heat Exchangers

ABSTRACT

For the development of industrial heat pump systems supplying a high-temperature heat source over 130°C, the authors have studied on cooling heat transfer of supercritical pressure fluids flowing in chevron-type plate heat exchangers (PHEs). In this study, to examine the effect of chevron angle on cooling heat transfer of supercritical pressure refrigerants, experiments were conducted for HFC134a and HFO1234ze(E) flowing in the PHEs with the chevron angles from 30° to 65°. In the experiments, cooling heat transfer coefficients were obtained in the wide range of bulk fluid enthalpy from vapor-like high temperature to liquid-like low temperature, changing the pressure in the reduced pressure range from 1.01 to 1.2 at the mass flow rates of 7 and 11 kg/min. Especially for the enthalpy region of the pseudo critical point and its vicinity in which good heat transfer appeared, the effect of chevron angle on heat transfer of supercritical pressure fluids was clarified based on the measurements. Furthermore, the effect of chevron angle was examined for the wide angle range from 0° to 90° with estimating the heat transfer coefficient for the angles 0° and 90° from appropriate correlations. Besides, the present data were compared with some conventional heat transfer correlations.     

Development of a novel calcium phosphate cement composed mainly of calcium sodium phosphate with high osteoconductivity

Two novel calcium phosphate cements (CPC) have been developed using calcium sodium phosphate (CSP) as the main ingredient. The first of these cements, labeled CAC, contained CSP, α-tricalcium phosphate (TCP), and anhydrous citric acid, whereas the second, labeled CABC, contained CSP, α-TCP, β-TCP, and anhydrous citric acid. Biopex^®-R (PENTAX, Tokyo, Japan), which is a commercially available CPC (Com-CPC), and OSferion^® (Olympus Terumo Biomaterials Corp., Tokyo, Japan), which is a commercially available porous β-TCP, were used as reference controls for analysis. In vitro analysis showed that CABC set in 5.7 ± 0.3 min at 22 °C and had a compressive strength of 86.0 ± 9.7 MPa after 5 days. Furthermore, this material had a compressive strength of 26.7 ± 3.7 MPa after 2 h in physiologic saline. CAC showed a statistically significantly lower compressive strength in the presence of physiologic saline and statistically significantly longer setting times than those of CABC. CABC and CAC exhibited apatite-forming abilities in simulated body fluid that were faster than that of Com-CPC. Samples of the materials were implanted into the femoral condyles of rabbits for in vivo analysis, and subsequent histological examinations revealed that CABC exhibited superior osteoconductivity and equivalent bioresorbability compared with Com-CPC, as well as superior osteoconductivity and bioresorbability compared with CAC. CABC could therefore be used as an alternative bone substitute material.     

Helicase‐Dependent Isothermal Amplification of DNA and RNA by Using Self‐Avoiding Molecular Recognition Systems

Assays that detect DNA or RNA (xNA) are highly sensitive, as small amounts of xNA can be amplified by PCR. Unfortunately, PCR is inconvenient in low‐resource environments, and requires equipment and power that might not be available in these environments. Isothermal procedures, which avoid thermal cycling, are often confounded by primer dimers, off‐target priming, and other artifacts. Here, we show how a “self avoiding molecular recognition system” (SAMRS) eliminates these artifacts and gives clean amplicons in a helicase‐dependent isothermal amplification (SAMRS‐HDA). We also show that incorporating SAMRS into the 3′‐ends of primers facilitates the design and screening of primers for HDA assays. Finally, we show that SAMRS‐HDA can be twofold multiplexed, difficult to achieve with HDA using standard primers. Thus, SAMRS‐HDA is a more versatile approach than standard HDA, with a broader applicability for xNA‐targeted diagnostics and research.     

Scaling dependence of electron transport in nano-scale Schottky barrier MOSFETs

The scaling dependence of electron transport in the double-gated Schottky barrier MOSFET (DG-SBT) below 10 nm is investigated in the framework of quantum transport theory, using non-equilibrium Green’s function method. Simulation results show that the current-voltage characteristics in ultra-small DG-SBT are characterized by both resonant and direct tunneling effects. The electron potential in the 10-nm-scale DG-SBT surrounded by Schottky barriers acts as a resonant cavity and produce a negative differential resistance due to resonant tunneling effect. While, further scaling shallows the depth of the cavity and makes it difficult to form resonance levels. Hence, at the scaling limit, direct tunneling currents simply dominate the current-voltage characteristics of DG-SBT.