Microwave-Assisted Chemistry: a Closer Look at Heating Efficiency

2009 ◽  
Vol 62 (3) ◽  
pp. 236 ◽  
Author(s):  
Richard Hoogenboom ◽  
Tom F. A. Wilms ◽  
Tina Erdmenger ◽  
Ulrich S. Schubert

Nowadays, microwave heating has evolved into a common tool for chemists based on its numerous advantages over conventional conductive heating. Surprisingly, the efficiency of microwave-assisted heating is still rather unexplored. In this contribution, we report our investigations concerning the heating efficiency of a variety of solvents including polar and apolar substances. Moreover, the effects of adding salt or passive heating elements on the microwave heating efficiency will be addressed. Finally, the heating efficiency of demineralized water is discussed at different volumes and with different microwave power levels in both monomode and multimode microwave synthesizers, demonstrating maximum average heating efficiencies of 10% for small-scale vessels (5 mL), 20% for medium-scale (50 mL), and 30% for large-scale microwave heating (400 mL).

Jurnal AKTUAL ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 47
Author(s):  
Aisah Aisah

Rice Milling Company is rice industry’s oldest and largest classified in Indonesia, which is able to absorb more than 10 million workers, handles more than 40 million tons of grain.  Rice Milling Company agro-industy is the central point, because this is where the main product is obtained in the form of rice and raw materials for advanced processing of food and industrial products.  Rice Miling Unit in the district of OKU Timur there is some skala, ranging form small-scale, medium-scale to large-scale.  Fuctional benefits of each different scale milling is also different.  The average rice farmers often sell gabahnya to the rice milling unit closest to the place residence, whether it is large-scale, medium and small.  Rice produced by the milling-grinding different quality.  Usually when a large-scale millimg yield of rice is cleaner than the other scale.  But it does not become a reference for milling grain milling usually depends on consumer demand.  The purpose of the study are : 1.  To determine levels of volume (tonnage) and the retention time of each service fuctional rice storage (barns) wich carried a different scale rice milling unit.  2.  To determine differences in the bebefits of economic transactions received by farmers and rice millers of different scale of business, especially when seen from the level of the milling costs, the purchase price of rice by rice milling unit, and the quality of milling services and service scale.  The result show that : the fuctional role of each is different milling.  Large-scale milling has three fuctional roles are : Processing, storage and distribution.  Medium-scale miling functional has two roles, namely : processing and distribution.  While small-scale rice milling unit has only two functional roles are : processing and storage.


2018 ◽  
Vol 39 (3) ◽  
pp. 1211
Author(s):  
Flávio De Moraes ◽  
Marcos Aurélio Lopes ◽  
Francisval De Melo Carvalho ◽  
Afonso Aurélio de Carvalho Peres ◽  
Fábio Raphael Pascoti Bruhn ◽  
...  

This study investigates the cost-effectiveness of 20 demonstration units (DUs) belonging to the "Balde Cheio" program. The units in question are from the state of Rio de Janeiro, Brazil, dating from January to December 2011, and are sorted according to the scale of production (small, medium and large). The data were analyzed using Predictive Analytical software (PASW) 18.0. The scale of production influenced the total cost of milk production, and therefore profitability and cost-effectiveness. The large-scale stratum showed the lowest total unit cost. The positive results in medium and large scales in milk production lead to optimal conditions for long-term production, with the capitalization of cowmen. The items regarding the effective operating cost (EOC) with the biggest influence on the costs of dairy activity in the small scale stratum were food, energy and miscellaneous expenses. In the medium scale, these were food, labor force, and miscellaneous expenses. Finally, in the large scale, they were food, labor force and energy. In the small and large scale, the items regarding the total cost with the biggest influence on the costs of dairy activity were food, labor force, and return on capital, while in the medium scale, they were food, return on capital, and labor force. The average break-even point of 14 of the DUs was higher than the average daily production.


2019 ◽  
Vol 10 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Jiake Li ◽  
Cong Mu ◽  
Chenning Deng ◽  
Menghua Ma

Abstract The storm water management models were established at three spatial scales (large, medium, and small) based on a sponge city pilot area in China to explore the hydrological and environmental effects of rainfall conditions and development modes. Results showed the following. (1) Total runoff reduction rates increased from 26.7% to 53.9% for the rainfall event of a 2-year recurrence period as the scale increased. For 5-year and above recurrence periods, total runoff reduction rates were 19.5–49.4%. These rates increased from the small to medium scale and slightly decreased from the medium to large scale. (2) The runoff coefficients were 0.87–0.29, which decreased from the small to medium scale and were basically constant from the medium to large scale. (3) The peak flow reduction rates decreased with increased recurrence periods. The rates increased initially and then decreased at the small scale, whereas the opposite trend occurred at the medium scale. (4) The reduction rates of pollutants were negatively correlated with recurrence periods under the three spatial scales. The pollution load reduction rates were 19.5–54.7%, which increased from the small to medium scale and were basically constant from the medium to large scale.


1987 ◽  
Vol 9 ◽  
pp. 247-248
Author(s):  
Yu. F. Knizhnikov ◽  
V.I. Kravtsova ◽  
I.A. Labutina

Remote-sensing methods in monitoring the glacierization of Mount EI‛ brus are used to produce base and dynamic maps, and to obtain quantitative information (dynamic indices) about the rate, intensity, and variations of the process. The monitoring system is divided, according to scope and territory covered, into small-scale for total glacierization and the periglacial zone, medium-scale for separate glaciers, and large-scale (detailed) for part of the glaciers or sectors of the adjoining slopes. The approximate relationship of even scales is 1 : 4. Small-scale monitoring remote-sensing systems are important for making maps showing the complex characteristics of the glaciological system. A series of maps was produced including geographical, those of high-altitude zones, slope and exposure angles, geological, glaciomorphological, climatic (temperature, precipitation, and winds), distribution of direct solar radiation, hydrological (source of streams), seats of avalanches, and landslides. All these data serve as a cartographical basis in monitoring the glacierization of Mount EI‛ brus. They are compiled from remotely sensed and Earth-based data. Current monitoring on a small scale includes observations of the conditions which determine the existence of the glacial system - this includes data on winter snowfall and the period of snow cover. These observations were obtained from meteorological and resource satellites, and from scanner data of medium and high resolution. Also important are observations of changes in the outline of glaciers, times of snowfall and character of the distribution of snow, and its redistribution due to avalanches and snowstorms. High-resolution space photographs, small-scale aerial photographs, and aerovisual observations provide the data for these observations. It has been determined that the area of the glaciers of Mount El‛ brus has been reduced by 1 % in the last 25 years, i.e. the rate of its deglacierization dropped sharply as compared to preceding decades. The role of quantitative information gains importance in the medium-scale level of monitoring. Topographical maps of separate glaciers compiled from aerial photographs or data from ground stereo-photogrammetric surveys constitute the base maps at this level. The main method used in monitoring were large-scale surveys from aircraft, perspective surveys from helicopters, and phototheodolite surveys. Multi-date surveys of the glaciers provide data about the changes in their outlines and height, the character of their relief, their moraines, the amount of snow accumulation and ablation in separate years, the surface rates of ice flow and their fluctuations. The techniques by which quantitative information is obtained about changes in the glaciers are derived from processing the data of multi-date surveys. The organization and techniques of phototheodolite surveys have been improved. A theory evolved for determining the surface-ice movement by stereo-photogrammetric means and the technique for it has also improved; algorithms and programs for machine processing of the data of multi-date surveys (ground and from aircraft) have been produced At this level of monitoring, it has been found that the retreat rate of most glaciers has slowed down and several glaciers are now in equilibrium. Several glaciers became active at the beginning of the 1970s and 1980s; this was accompanied by an increase in their height and forward movement. For example, activation of Kyukyurtlyu Glacier has been recorded (higher surface and increasing flow rate) which has caused the glacier to move forward 100 m. Surveys at an interval of 2 years recorded the beginning of the process of retreat of this glacier. Detailed monitoring is used to detect the mechanism of the dynamic processes and to study it on local representative sectors. On a glacier it may take the form of annual surveys of its tongue, which makes it possible to observe the processes of formation of moraines and glacio-fluvial relief. Studies may also be made of the mechanism of the movement of avalanches and landslides, deducing their quantitative characteristics and appraising the results of avalanches and landslides. Multi-date surveys of sectors of the slopes provide information about processes in the periglacial zone. At this level, regularly repeated ground stereo-photogrammetric surveys are the main means of observation. Glaciological remote-sensing monitoring provides a wealth of data for theoretical development in the field of glaciology. It makes it possible to forecast and produce warnings about hazardous processes and phenomena.


2014 ◽  
Vol 556-562 ◽  
pp. 916-920
Author(s):  
Yu Huan Li ◽  
Deng Qiu Li ◽  
Jie Wu

The spatial variability of single ecological factors of the farmland and the synergies among the ecological factors were studied by using geostatistical analysis and factorial kriging analysis (FKA).The results show that all of the spherical models of the co-variogram can be grouped into four parts: the nugget part, the small-scale part, the medium-scale part, and the large-scale part. The mean value of the small-scale range (1.12-1.85 km) is approximately 1.50 km, that of the medium-scale range (3.40-4.10 km) is approximately 3.8 km, and that of the large-scale range (9.35-10.10 km) is approximately 9.8 km. The correlations between each factor on the four scales vary, and the correlation between each factor on the medium scale is the strongest. In this paper, the ecological factors of the farmland on the medium scale have relatively consistent variability and sources, indicating that all of the factors on that scale have a high coordination.


2021 ◽  
Vol 17 ◽  
pp. 2543-2552
Author(s):  
Robin Klintworth ◽  
Garreth L Morgans ◽  
Stefania M Scalzullo ◽  
Charles B de Koning ◽  
Willem A L van Otterlo ◽  
...  

A wide range of N-(ethoxycarbonylmethyl)enaminones, prepared by the Eschenmoser sulfide contraction between N-(ethoxycarbonylmethyl)pyrrolidine-2-thione and various bromomethyl aryl and heteroaryl ketones, underwent cyclization in the presence of silica gel to give ethyl 6-(hetero)aryl-2,3-dihydro-1H-pyrrolizine-5-carboxylates within minutes upon microwave heating in xylene at 150 °C. Instead of functioning as a nucleophile, the enaminone acted as an electrophile at its carbonyl group during the cyclization. Yields of the bicyclic products were generally above 75%. The analogous microwave-assisted reaction to produce ethyl 2-aryl-5,6,7,8-tetrahydroindolizine-3-carboxylates from (E)-ethyl 2-[2-(2-oxo-2-arylethylidene)piperidin-1-yl]acetates failed in nonpolar solvents, but occurred in ethanol at lower temperature and microwave power, although requiring much longer time. A possible mechanism for the cyclization is presented, and further functionalization of the newly created pyrrole ring in the dihydropyrrolizine core is described.


Author(s):  
Neeru Yadav

Abstract: Six Sigma is a tool which helps industries to control the defects and all other issues which can be possible factors to reduce the growth of the company. It was seen that in large scale industries, the Six Sigma is used form previous decades but when goes to small and medium scale industries, there is lack of implementation of Six Sigma and its tools, so in present review paper, various research papers selected in which small and medium scale industries are selected. In this paper all possible aspects of the Six Sigma is presented in detail. Keywords: Six Sigma, Tools, Small Scale Industries, DMAIC approach, Manufacturing Industries


1976 ◽  
Vol 13 (10) ◽  
pp. 1422-1432 ◽  
Author(s):  
Andrew D. Miall

The Eureka Sound Formation of northern Banks Basin is a deltaic unit of Paleocene to Eocene age. A basal member of shale, approximately 100 m thick, passes vertically and, in part, laterally into a succession of sand, silt, shale, and lignitic coal approximately 1000 m thick, which is referred to as the cyclic member because of the abundance of coarsening-upward cycles, averaging 7.4 m in thickness.Sand beds in the cyclic member can be divided into four lithofacies: (1) A facires dominated by medium- to large-scale planar crossbedding, formed by channel processes, including lateral point bar accretion, in the delta plain environment. (2) A predominance of medium-scale trough and (minor) planar crossbeds, formed by migrating dunes in distributary mouth bar sands. (3) A predominance of small-scale ripple-marks, formed by low energy, unimodal currents in distal distributary mouth sands. (4) A lack of current structures, indicating quiet-water, interdeltaic and prodeltaic deposition. The distribution of these four facies outlines a series of small lobate deltas.Paleocurrent data suggest a pattern of radiating distributaries within each delta lobe. Directional variance, when analyzed at various levels of the sedimentary structure hierarchy, provides information regarding channel sinuosity and enables comparisons to be made with other deltaic deposits. High variance for the directions of the distributaries is consistent with a fluvially dominated delta.


2001 ◽  
Vol 5 (3) ◽  
pp. 151-164 ◽  
Author(s):  
E. Balakrishnan ◽  
M. I. Nelson ◽  
X. D. Chen

The use of microwave heating to initiate combustion synthesis has been increasingly investigated in recent years because of its advantages over traditional methods. A simple mathematical model is used to model these experiments. The microwave power absorption term is modelled as the product of an Arrhenius reaction term with a function that decays exponentially with distance. The former represents the temperature-dependent absorption of the microwaves whereas the latter describes the penetration of the material by the microwaves. Combustion kinetics are modelled as a first-order Arrhenius reaction.


2014 ◽  
Vol 955-959 ◽  
pp. 3828-3834
Author(s):  
Wei Cheng Zou ◽  
G. R. Xiao

The correlation between Normalized Difference Vegetation Index (NDVI) and environmental factors is examined at different scales and locations in world heritage of Wuyi Mountain by wavelet coherency. These factors are elevation, slope, aspect, distance to nearest resident, distance to nearest road , and distance to nearest river along two transects based on data of DEM, residents, roads, rivers and ALOS remote sensing image in 2009.The results show that:(1) The relationships between NDVI and environmental factors change along with scale. The relationships between NDVI and environmental factors in the first transect are all weak at small scale (<480m). At medium scale (480-7680m), NDVI is significantly correlated with elevation, slope, resident , and road. At large scale (>7680m), NDVI is significantly correlated with elevation, resident and river. For the second transect, NDVI is significantly correlated with aspect at small scale; and significantly correlated with elevation, aspect, slope and river at medium scale; and significantly correlated with elevation, aspect, and slope at large scale. Thus elevation is the dominant controlling factors on the vegetation cover.(2)The relationships between NDVI and environmental factors also change when location changes. There is positive correlation between NDVI and elevation below the altitude of 600 m and the windward side of the southeast monsoon above 600m, while it is negative in the leeward side above 600m. Besides, NDVI is directly related with road, resident, slope, and river in the areas where the elevation is below 1200m, but inversely above 1200m.


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