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2022 ◽  
Vol 210 ◽  
pp. 114419
Author(s):  
Daniel K. Schreiber ◽  
Elizabeth J. Kautz ◽  
Matthew J. Olszta ◽  
Karen Kruska ◽  
Angela Y. Gerard ◽  
...  

MAUSAM ◽  
2021 ◽  
Vol 58 (2) ◽  
pp. 177-188
Author(s):  
K. K. CHAKRABARTY ◽  
A. K. NATH ◽  
S. SENGUPTA

During the pre-monsoon months of March, April and May the weather over Kolkata is generally very uncomfortable due to high temperature and relative humidity. During this season Kolkata is affected by the nor’wester activity. Generally the nor’wester activity is defined as a disastrous weather activity and is locally called as ‘Kaalbaisakhi’ as it is ‘kaal’ or destruction during Bengali Baishakh (April-May) month over Bengal. However the downdraft associated with the nor’wester brings cool air and temperature sometimes drops by as much as 8 to 9 degree Celsius and the atmosphere becomes comfortable for some period. This is an entirely different and positive aspect of nor’wester.The human comfortability depends upon many weather parameters apart from human physiological parameters. However the primary weather factors are air temperature and relative humidity especially for tropical areas. Many authors have worked on this and the well accepted formula for thermal index THI or Discomfort Index DI is taken from Thom (1957,1958) which is a function of dry bulb and wet bulb temperature i.e., THI or DI = 0.4 (Ta + Tw) + 15 where temperature is in ºF and is 0.72 (Ta + Tw) + 40.6 where temperature is in ºC. Various stages of comfortability are classified viz., (i) Discomfortable (ii) Partial discomfortable and (iii) Comfortable. Neglecting the effect of wind and further simplifying the equation for DI as a function of (Ta + Tw) the range varies from 27 to 55 in increasing order of temperature.During the pre-monsoon months when the climate over Kolkata is very sultry and uncomfortable, people generally desire the onset of nor’wester for some temporary relief although it results into destruction. The nor’wester makes the weather comfortable after its occurrence and remains comfortable for 10 to 12 hours and some time even for a day. The present study is made taking six years data over Kolkata, both Alipore and Dum Dum. It is seen that except early morning of March the remaining period of pre-monsoon season is found to be uncomfortable climatologically. In the present study there were 91 occasions of squalls and it is found that most of the squalls occurred during the month of April and May and on most of the occasions nor’wester made the weather comfortable for a large part of the day in the month of April. By the end of May nor’wester activity also brought relief but not to that extent as in March and April to the people of Kolkata and neighbourhood.


2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Zhi-Kun Wang ◽  
Caoxing Huang ◽  
Jun-Lei Zhong ◽  
Yi Wang ◽  
Lv Tang ◽  
...  

Abstract Chinese hickory shell, a by-product of the food industry, is still not utilized and urgent to develop sustainable technologies for its valorization. This research focuses on the systematical evaluation of degraded products and xylooligosaccharide production with high yield from the shell via hydrothermal process. The pretreatment was carried out in a bath pressurized reactor at 140–220 °C for 0.5–2 h. The results indicated that the pretreatment condition strongly affected the chemical structures and compositions of the liquid fraction. The maximum yield of XOS (55.3 wt%) with limitation of by-products formation was achieved at 160 °C for 2 h. High temperature (220 °C) and short time (0.5 h) contributed to hydrolysis of xylooligosaccharide with high DP to yield 37.5 wt% xylooligosaccharide with DP from 2 to 6. Xylooligosaccharide obtained mainly consisted of xylan with branches according to the HSQC NMR analysis. Overall, the production of XOS with a high yield from food waste will facilitate the valorization of food waste in the biorefinery industry. Graphical Abstract


2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Liang Zhang ◽  
Weimin Long ◽  
Sujuan Zhong

AbstractThe thermo-mechanical reliability of IMCs (Ni3Sn4, Cu3Sn, Cu6Sn5) solder joints and Sn-3.9Ag-0.6Cu solder joints was investigated systematically in 3D chip stacking structure subjected to an accelerated thermal cyclic loading based on finite element simulation and Taguchi method. Effects of different control factors, including high temperature, low temperature, dwell time of thermal cyclic loading, and different IMCs on the stress-strain response and fatigue life of solder joints were calculated respectively. The results indicate that maximum stress-strain can be found in the second solder joint on the diagonal of IMC solder joints array; for Sn-3.9Ag-0.6Cu solder joints array, the corner solder joints show the obvious maximum stress-strain, these areas are the crack propagated locations. The stress-strain and fatigue life of solder joints is more sensitive to dwell temperature, especially to high temperature; increasing the high temperature, dwell time, or decreasing the low temperature, can reduce the stress-strain and enlarge the fatigue life of solder joints. Finally, the optimal design in the 3D-IC structure has the combination of the Cu6Sn5/Cu3Sn, 373 K high temperature, 233 K low temperature, and 10 min dwell time. The fatigue lives of Sn-3.9Ag-0.6Cu under 218–398 K loading in the 3D assembly based on the creep strain are 347.4 cycles, which is in good agreement with experimental results (380 cycles).


2021 ◽  
Author(s):  
Jianwei Ben ◽  
Jiangliu Luo ◽  
Zhichen Lin ◽  
Xiaojuan Sun ◽  
Xinke Liu ◽  
...  

Abstract To introduce voids at certain height in AlN layer by a simple method is meaningful but challenging. In this work, the AlN/sapphire template with AlN interlayer structure has been designed and grown by metal-organic chemical vapor deposition. Then the AlN template was annealed at 1700℃ for an hour to introduce the voids. It has been found that the voids were formed in the AlN layer after high temperature annealing and the positions of the voids were mainly distributed around the AlN interlayer. Meanwhile, the dislocation density of the AlN template has been decreased from 5.26×109 cm-2 to 5.10×108 cm-2. This work provides a possible method to introduce voids in AlN layer at designated height, which will benefit the design of AlN-based devices.


2021 ◽  
Vol 7 (4) ◽  
pp. 139-152
Author(s):  
José Nhanga

The present work aimed to study a family of solid ceramic electrolytes based on magnesium oxide doped zirconium oxide, usually identified as Mg-PSZ (zirconia partially stabilized with magnesia), used in the manufacture of oxygen sensors for molten metals. A set of electrolytes was prepared by mechanical (milling) and thermal (sintering) processing, varying the composition in magnesia and the cooling rate from the sintering temperature. These two parameters are essential in terms of phase composition and microstructure of Mg-PSZ, determining the behavior of these materials. The structural and microstructural characterization was done by means of X-ray diffraction (XRD). The electrical properties were analyzed by impedance spectroscopy in air. In general, the results obtained from various concentrations of dopant, different cooling rates and the same sintering step condition showed an increased conductivity for samples with predominance of high temperature stable phases (tetragonal and cubic).


2021 ◽  
Author(s):  
Dajiang Zhu ◽  
Yu Fan ◽  
Huali Zhang ◽  
Yufei Li ◽  
Lin Zhang ◽  
...  

Abstract The Longwangmiao (referred to as LM) gas field in southwest China has characteristics of high temperature (144~156 °C), high pressure(75~76 MPa), and high production rate (70~100×104 m3/d). Serious well integrity problems were encountered in the development process; 21% of 56 wells were subjected to sustained casing pressure (SCP)(≥20 MPa). Downhole leak detection logs indicated the main cause was tubing connection leakage at a depth range of 0~2400 m. Wellhead growth was present in 33 wells and 4 wells exhibited gas leakage through wellhead valves. Theoretical analysis and field tests were conducted to investigate and manage well integrity problems. A method to calculate the allowable pressure for different annuli was proposed based on string strength analysis, and downhole leak detection was conducted using ultrasonic leak detection method. A multi-string mechanical model to predict wellhead growth was established and the threshold values were calculated under different gas rates. According to the structure of wellhead, a method based on ultrasonic phased array to detect the work state of the wellhead was adopted, which measured the actual thickness of key valves to evaluate service life. For wells with SCP, the allowable pressure for different annuli was calculated and the pressure management charts were drawn and all wells were in steady production. Downhole leak detection showed that SCP in the A annulus (annulus between the tubing and production casing) was caused by connection leakage of tubing. In newly completed wells, a premium connection was adopted based on tests under cyclic structural and environmental thermal loads that the connections may encounter at various production phases, and the total ratio of SCP in newly completed wells decreased by 31.4%. Wellhead growth was predicted and compared with actual data, which showed an increase in average accuracy of 20~30% compared to the results from the WellCAT software. Sensitivity analysis revealed that the length of un-cemented casing and the production rate were the critical factors affecting the wellhead growth. The valve leakage of FF level material wellhead was caused due to corrosion after the removal of the coating, and no leakage was detected in the HH level material wellhead. Thickness survey showed that the average reduction was 0.085 mm~0.23 mm for HH wellhead, and 1.12 mm~2.24 mm for FF wellhead.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
D. Kiphart ◽  
Y. Harkavyi ◽  
K. Balin ◽  
J. Szade ◽  
B. Mróz ◽  
...  

AbstractWe used the topological insulator (TI) Bi2Te3 and a high-temperature superconductor (HTSC) hybrid device for investigations of proximity-induced superconductivity (PS) in the TI. Application of the superconductor YBa2Cu3O7-δ (YBCO) enabled us to access higher temperature and energy scales for this phenomenon. The HTSC in the hybrid device exhibits emergence of a pseudogap state for T > Tc that converts into a superconducting state with a reduced gap for T < Tc. The conversion process has been reflected in Raman spectra collected from the TI. Complementary charge transport experiments revealed emergence of the proximity-induced superconducting gap in the TI and the reduced superconducting gap in the HTSC, but no signature of the pseudogap. This allowed us to conclude that Raman spectroscopy reveals formation of the pseudogap state but cannot distinguish the proximity-induced superconducting state in the TI from the superconducting state in the HTSC characterised by the reduced gap. Results of our experiments have shown that Raman spectroscopy is a complementary technique to classic charge transport experiments and is a powerful tool for investigation of the proximity-induced superconductivity in the Bi2Te3.


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