Interannual Influences of the Surface Potential Vorticity Forcing over the Tibetan Plateau on East Asian Summer Rainfall

The influences of interannual surface potential vorticity forcing over the Tibetan Plateau (TP) on East Asian summer rainfall (EASR) and upper-level circulation are explored in this study. The results show that the interannual EASR and associated circulations are closely related to the surface potential vorticity negative uniform leading mode (PVNUM) over the TP. When the PVNUM is in the positive phase, more rainfall occurs in the Yangtze River valley, South Korea, Japan, and part of northern China, less rainfall occurs in southern China, and vice versa. A possible mechanism by which PVNUM affects EASR is proposed. Unstable air induced by the positive phase of PVNUM could stimulate significant upward motion and a lower-level anomalous cyclone over the TP. As a result, a dipole heating mode with anomalous cooling over the southwestern TP and anomalous heating over the southeastern TP is generated. Sensitivity experiment results regarding this dipole heating mode indicate that anomalous cooling over the southwestern TP leads to local and northeastern Asian negative height anomalies, while anomalous heating over the southeastern TP leads to local positive height anomalies. These results greatly resemble the realistic circulation pattern associated with EASR. Further analysis indicates that the anomalous water vapor transport associated with this anomalous circulation pattern is responsible for the anomalous EASR. Consequently, changes in surface potential vorticity forcing over the TP can induce changes in EASR.

Ultra-sensitive all-optical comagnetometer with laser heating

Ultra-sensitive comagnetometers, which are designed to detect nuclear-and electron-spin-dependent interaction, have important applications ranging from basic research to inertial navigation systems (INSs). Unfortunately, electric heating, which is typically used in comagnetometers, introduces systematic errors because of the unavoidable generation of a modulated magnetic field. In this study, we investigate and introduce K-Rb-21Ne comagnetometer that uses laser heating for the first time, when operated in the spin-exchange relaxation free (SERF) regime. The performance of the comagnetometer, which is equipped with both laser heating and electric heating, is investigated, and the two heating modes are compared. The temperature characteristics of the comagnetometer are studied theoretically and experimentally. By optimizing the operating temperature and power density of the pump-light, an equivalent rotation sensitivity of 2.5×10^(-7) rad/s/√Hz@1Hz is achieved in laser heating mode. The improvement of laser-heating technology could prove essential to reduce electron relaxation and increase the low-frequency sensitivity of comagnetometers. Our results indicate that laser heating can make comagnetometers more suitable for applications in basic research (fifth force, dark matter, etc.), INSs, and other accurate measurements of electronic and nuclear precession.

Spectroscopic study on peculiarities of fumed silica hydridesilylation with triethoxysilane under fluidized bed conditions

Fumed silica has found widespread application in industry due to variety of fascinating properties. Owing to its specific manufacturing process, it consists of finely dispersed particles and is featured with large specific surface area covered by profoundly reactive silanol groups which are available for chemical grafting. Spherical shape of fumed silica particles and lacking porosity provides a space-filling structure. These characteristics implement the fume silica’s utilization as high-surface-area carriers for various catalysts, i.e. metallic nanometer-sized particles, organic moieties, etc. Currently a great attention is called to on-surface grafting to improve the silica-based carrier. Most of research is carried out in area of liquid phase chemistry involving an abundance of expensive and often toxic solvents while the space-filling properties of silica are favoring reactions in fluidized bed conditions. In current research fumed silica (A-300) was a subject for hydridesilylation with triethoxysilane under fluidized bed conditions. In all synthesis reported in current research the insignificant amount of solvent (1.00 wt. % of the amount used in typical wet-chemical modifications method) was spent for the silica surface silylation. While the mass ratio of silica/TES was kept constant, other conditions, i.e. solvent/catalyst presence, surface pretreatment, additional treatment with water, and the fluidized bed heating mode have been varied. FTIR spectroscopy revealed the interaction between groups of triethoxysilane and silica surface silanol groups and demonstrated the effect of modification conditions on the density of the hydridesilyl groups coverage. The results of FTIR spectroscopic studies have confirmed the presence of grafted silicon hydride groups on the surface of modified silica, as well as the presence of ethoxy and/or silanol groups – either intact or formed due to hydrolysis of the ethoxy groups. Titrimetric and spectrophotometric analysis was performed to estimate the concentration of grafted SiH groups (in all samples prepared under fluidized bed conditions their concentration ranged within about 0.28–0.55 mmol/g as dependent on the reaction conditions). Other important aspects of fluidization such as the presence of solvent and/or hydrolyzing agent, bed heating mode and the effect of the silica sample thermal pre-treatment are also discussed.

Contrastive Analysis on the Ventilation Performance of a Combined Solar Chimney

A combined solar chimney is proposed in this paper that integrates an inclined-roof solar chimney with a traditional Trombe wall. The ventilation performance of the combined solar chimney is analyzed numerically and then compared with the Trombe wall and the inclined-roof solar chimney. The feasibility of different operation modes and the ventilation effect under different environment conditions are also discussed. The results show that when the ambient temperature ranges from 298 to 303 K in the summer, a natural ventilation mode is appropriate. Otherwise, an anti-overheating mode is recommended. When the ambient temperature is lower than 273 K in the winter, a space heating mode has a better heating effect. A preheating mode can be employed to improve the indoor air quality when the ambient temperature is higher than 278 K. The simulation results indicates that the ventilation effect of the combined solar chimney is better than that of the Trombe wall and the inclined-roof solar chimney, and the problem of overheating can be avoided. The study provides guidance for the optimal operation of a combined solar chimney.

Quality Formation of Adzuki Bean Baked: From Acrylamide to Volatiles under Microwave Heating and Drum Roasting

Baked adzuki beans are rich in tantalizing odor and nutritional components, such as protein, dietary fiber, vitamin B, and minerals. To analyze the final quality of baked beans, the acrylamide and volatile formation of adzuki beans were investigated under the conditions of microwave baking and drum roasting. The results indicate that the acrylamide formation in baked adzuki beans obeys the exponential growth function during the baking process, where a rapid increase in acrylamide content occurs at a critical temperature and low moisture content. The critical temperature that leads to a sudden increase in acrylamide content is 116.5 °C for the moisture content of 5.6% (w.b.) in microwave baking and 91.6 °C for the moisture content of 6.1% (w.b.) in drum roasting. The microwave-baked adzuki beans had a higher formation of the kinetics of acrylamide than that of drum-roasted beans due to the microwave volumetric heating mode. The acrylamide content in baked adzuki beans had a significant correlation with their color due to the Maillard reaction. A color difference of 11.1 and 3.6 may be introduced to evaluate the starting point of the increase in acrylamide content under microwave baking and drum roasting, respectively. Heating processes, including microwave baking and drum roasting, for adzuki beans generate characteristic volatile compounds such as furan, pyrazine, ketone, alcohols, aldehydes, esters, pyrroles, sulfocompound, phenols, and pyridine. Regarding flavor formation, beans baked via drum roasting showed better flavor quality than microwave-baked beans.

Evaluation of the intrinsic thermal performance of an envelope in the summer period

Ensuring the proper thermal performance of a building’s envelope upon reception is an important stage in the life cycle of the building. Several methods already exist for this purpose, and continue to be improved, such as co-heating, ISABELE, EPILOG, QUB and SEREINE. All these methods follow the common protocol consisting of heating the measured building. These measurement protocols quantify the dynamic evolution of interior and outdoor temperatures, and the thermal power injected into the building and these data are used in calibration algorithms to determine, by an inverse method to deduce a heat loss value. These methods require a difference of a few degrees between the interior and the exterior which can cause in summer periods a risk of damaging the building, as the outside temperature may already be high. The objective of this work is to explore the possibility of determining the intrinsic thermal performance of a building’s envelope in the summer period using a cooling system. This work leans on an experiment of a square meter scale cell and explore the capacities and limitations of the method at this scale by varying several stress parameters of the enclosure. Results in cooling mode are also compared to heating mode.

Prospects of the microwave heating application in fruits of rowan processing

В Мичуринском государственном аграрном университете исследована возможность применения СВЧ-нагрева с целью повышения антиоксидантной ценности пюре из плодов рябины обыкновенной. В качестве стандарта при определении суммарного содержания антиоксидантов на приборе «Цвет Яуза 01-АА» выступил кверцетин. Установлено, что с увеличением температуры СВЧ-нагрева плодов рябины до 70 °С наблюдается повышение суммарного содержания антиоксидантов (ССА). Увеличение содержания антиоксидантов в свободном состоянии обусловлено происходящими в результате СВЧ-нагрева рябины изменениями клеточных структур. Установлен оптимальный режим СВЧ-нагрева плодов рябины: время - 80 сек, мощность - 700 Вт, удельная работа - 560 Вт/г·с, при котором обеспечивается максимальное увеличение ССА до 131,9 мг/100 г (507,3 мг/100 г с.в.) при содержании сухих веществ 26,2 %, что в 1,5 и 1,4 раза больше по сравнению с пюре из свежих и бланшированных плодов. Повышение антиоксидантной ценности рябинового пюре после СВЧ-нагрева обусловлено изменением содержания антоцианов, флавонолов и катехинов, значения которых увеличиваются соответственно в 3,9, 1,6 и 1,1 раза по сравнению с пюре из свежих плодов и в 1,1, 1,2 и 1,3 раза по сравнению с пюре из бланшированных плодов. При выбранном режиме СВЧ-нагрева быстрее наступает стабилизация окраски пюре из-за инактивации ферментов и в меньшей степени термической деградации антоцианов. Рябиновое пюре, полученное с применением СВЧ-нагрева, рекомендовано при производстве продуктов для здорового и функционального питания, в том числе кондитерских и хлебо-булочных изделий. The Michurinsk State Agrarian University investigated the possibility of using microwave heating in order to increase the antioxidant value of rowan puree. Quercetin was used as a standard for determining the total antioxidants content on the Tsvet Yauza 01-AA device. It was found that with an increase in the microwave heating temperature of rowan fruits to 70 °C, an increase in the total antioxidants content is observed. An increase in the content of antioxidants in a free state is due to changes in cellular structures occurring as a result of microwave heating of rowan. The optimal microwave heating mode for rowan fruits was established: time - 80 seconds, power - 700 W, specific work - 560 W / g·s, at which is ensured the maximum increase of total antioxidants content to 131.9 mg / 100 g (507.3 mg / 100 g dry matter) and a dry matter content of 26.2 %, which is 1.5 and 1.4 times more compared to fresh and blanched fruit puree. An increase in the antioxidant value of rowan puree after microwave heating is due to a change in the content of anthocyanins, flavonols and catechins, the value of which increases by 3.9, 1.6, 1.1 times, respectively, compared with fresh fruit puree and by 1.1, 1.2, 1.3 times compared to blanched fruit puree. With the selected microwave heating mode, the stabilization of the puree color occurs faster due to inactivation of enzymes and a lesser degree of thermal degradation of anthocyanins. Rowan puree obtained using microwave heating is recommended for the production of products for healthy and functional nutrition, including confectionery and bakery products.

OPERATION ANALYSIS OF THE AIR-SOURCE HEAT PUMP USING TRNSYS SIMULATION TOOL

In order to achieve ambitious goals for energy efficiency and requirements for near zero energy buildings, various technological solutions enabling the use of renewable energy are proposed and applied. One such rapidly spreading technology is heat pumps. However, the use of air-­to-­water heat pumps in countries where the cold season is cold and humid has unfavourable conditions for the operation of this equipment during the heating season. As a result, the performance efficiency of the equipment decreases. This article presents the simulation results of an air-­to-­water heat pump operation in Lithuania using the TRNSYS modelling tool; its nominal heating capacity is 6.55 kW. The model was calibrated using real data obtained at Vilnius Gediminas Technical University when measurements were performed under heat pump freezing conditions. The seasonal performance factor of the heat pump heating mode was determined during the calculation. Parametric analysis of the model was also performed, when sensitivity of the model to the initial climatic data was observed. Comparable results are obtained for Vilnius, Prague and London.

Optimization of a radiant system for hydrothermal performance using Taguchi and utility concept

Radiant floor panel technology is gaining popularity as an alternative system over conventional heating, ventilation and, air conditioning system (HVAC) to maintain the room temperature for the desired comfort. This research paper aims to optimize the hydrothermal performance of a radiant system by implementing the Taguchi technique and utility concept for cooling and heating mode of operation. Five geometrical and thermal parameters such as pipe diameter, pipe spacing, concrete layer thickness, wall temperature, and inlet and outlet water temperature difference with three levels are chosen as controlling factors to perform optimization. Considering five parameters and three levels, a total of 27 trial runs (L27) are constructed and computed by mathematical calculation. Two different sets of optimum parameters are obtained for maximizing heat flux and minimizing pressure drop. Further, the utility concept is employed to get a single set of parameters to achieve maximum utilization of the radiant system. Taguchi analysis revealed that thermal parameters like temperature difference and wall temperature are the most influential parameters to reach maximum heat transfer and minimum pressure drop followed by geometrical parameters like pipe spacing and diameter for heat flux and pressure drop, respectively. Providing more weightage to heat flux than pressure drop, utility analysis showed 32% and 42% augmentation in heat flux for cooling and heating mode respectively, at the cost of an increase in pressure drop.