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Experimental Investigation of the Cooling Capacity of Gaseous Carbon Dioxide in Free Jet Expansion for Use in Portable Air-Cooling Systems

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Open Journal of Applied Sciences 2018年第2期8卷 62-72页

作者： Chady Al Sayed Ludwig Vinches stéphane hallé Department of Mechanical Engineering école de Technologie Supérieure Montreal Canada

This paper investigates the possibility of using the free expansion of gaseous CO2 in portable air-cooling systems. The cooling capacity of the gaseous CO2 free jet expansion was calculated using three different approaches and the results showed that the simplified calculations would give approximated cooling values with an 11.6% maximum error. The mass flow rate, upstream pressure and cooling capacity of the gaseous CO2 decreased with time. A maximum 48.5 watts of cooling was recorded at minute 4 and a minimum value of 10.4 watts at the end of the test. The drop in cooling capacity is due to the evaporation of the liquid CO2 inside the small cylinder which cools the two-phase CO2 mixture and causes a pressure drop (from 6 MPa to 2.97 MPa), which also affects the mass flow rate of gaseous CO2 exiting the orifice (from 0.56 g/s to 0.24 g/s). If this cooling technique is to be considered in portable compact-cooling systems, the mass, pressure and cooling capacity drop with time must be solved. One of the solutions could be to cover the cylinder with a heating coat to compensate for the heat absorbed by the evaporation of the liquid CO2.

关键词： Gaseous CO2 Free Jet Expansion Cooling Capacity Compact Air-Cooling Technique

Validation of a Wearable Biometric System’s Ability to Monitor Heart Rate in Two Different Climate Conditions under Variable Physical Activities

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E-Health Telecommunication Systems and Networks 2017年第2期6卷 19-30页

作者： Chady Al Sayed Ludwig Vinches stéphane hallé Department of Mechanical Engineering école de Technologie Supérieure Montreal Canada

Research has proven the importance of cooling garments in reducing heat stress, especially for workers in extreme environments. The currently available cooling capacity of these garments should be controlled for improving their efficiency and autonomy. In this study, we investigated the Hexoskin wearable biometric shirt’s capacity to monitor heart rate. Twelve male volunteers wore a Hexoskin biometric shirt and Polar®H7 heart rate sensor and they completed two identical tests under two different climate conditions (25°C ± 0.5°C;39% ± 1% relative humidity and 31°C ± 0.5°C;60% ± 1% relative humidity). The results from four different statistical methods show a high correlation and an absence of significant differences between the Polar? and Hexoskin systems in monitoring the subjects’ heart rates. The Hexoskin wearable biometric shirt can be used to monitor the heart rate of humans in moderate or hot and humid climates under variable physical activities, regardless of their age, weight or height.

关键词： Hexoskin Biometric System Heart Rate Hot and Humid Environments Physical Activity

Acceptor doping and actuation mechanisms in Sr-doped BiFeO_(3)-BaTiO_(3)ceramics

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Journal of Materiomics 2024年第1期10卷 57-69页

作者： Ziqi Yang Yizhe Li Bing Wang Juncheng Pan Annette K.Kleppe David A.hall Department of Materials University of ManchesterM139PLManchesterUK Diamond Light Source Ltd. Harwell Science and Innovation CampusOX110DEDidcotUK

BiFeO_(3)-BaTiO_(3)(BF-BT)ceramics are important multiferroic materials,which are attracting significant attention for potential applications in high temperature lead-free piezoelectric *** the present study,the effects of Sr^(2+)as an acceptor dopant for Bi^(3+),in the range from 0 to 1.0%(in mole),on the structure and ferroelectric/piezoelectric properties of 0.7BiFeO_(3)-0.3BaTiO_(3)ceramics were *** use of a post-sintering Ar annealing process was found to be an effective approach to reduce electrical conductivity induced by the presence of electron holes associated with reoxidation during cooling.A low Sr dopant concentration(0.3%,in mole)yielded enhanced ferroelectric(P_(max)∼0.37 C/m^(2),P_(r)∼0.30 C/m^(2))and piezoelectric(d_(33)∼178 pC/N,k_(p)∼0.27)properties,whereas higher levels led to chemically heterogeneous core-shell structures and secondary phases with an associated decline in *** electric field-induced strain of the Sr-doped BF-BT ceramics was investigated using a combination of digital image correlation macroscopic strain measurements and in-situ synchrotron X-ray *** of the intrinsic(lattice strain)and extrinsic(domain switching)contributions to the electric field induced strain indicated that the intrinsic contribution dominated during the poling process.

关键词： Bismuth ferrite-barium titanate Acceptor doping Electroceramics Piezoelectricity In-situ X-ray diffraction

Arbuscular mycorrhizal fungi regulate plant mineral nutrient uptake and partitioning in iron ore tailings undergoing eco-engineered pedogenesis

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Pedosphere 2024年第2期34卷 385-398页

作者： Zhen LI Songlin WU Yunjia LIU Qing YI Merinda hall Narottam SAHA Junjian WANG Yuanfang HUANG Longbin HUANG College of Land Science and Technology China Agricultural UniversityBeijing 100193China Centre for Mined Land Rehabilitation Sustainable Minerals InstituteThe University of QueenslandBrisbaneQLD 4072Australia Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control School of Environmental Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China

Excess available K and Fe in Fe ore tailings with organic matter amendment and water-deficiencies may restrain plant colonization and growth,which hinders the formation of eco-engineered soil from these tailings for sustainable and cost-effective mine site *** mycorrhizal(AM)fungi are widely demonstrated to assist plant growth under various unfavorable ***,it is still unclear whether AM symbiosis in tailings amended with different types of plant biomass and under different water conditions could overcome the surplus K and Fe stress for plants in Fe ore tailings,and if so,by what ***,host plants(Sorghum *** ***),either colonized or noncolonized by the AM fungi(Glomus spp.),were cultivated in lucerne hay(LH,C:N ratio of 18)-or sugarcane mulch(SM,C:N ratio of 78)-amended Fe ore tailings under well-watered(55%water-holding capacity(WHC)of tailings)or water-deficient(30%WHC of tailings)*** mycorrhizal colonization,plant growth,and mineral elemental uptake and partitioning were *** indicated that AM fungal colonization improved plant growth in tailings amended with plant biomass under water-deficient *** mycorrhizal fungal colonization enhanced plant mineral element uptake,especially P,both in the LH-and SM-amended tailings regardless of water ***,AM symbiosis development restrained the translocation of excess elements(i.e.,K and Fe)from plant roots to shoots,thereby relieving their *** AM fungal roles in P uptake and excess elemental partitioning were greater in LH-amended tailings than in SM-amended *** deficiency weakened AM fungal colonization and functions in terms of mineral element uptake and *** findings highlighted the vital role AM fungi played in regulating plant growth and nutrition status in Fe ore tailings technosol,providing an important basis for involvement of AM fungi in the eco-engineered pedo

关键词： Fe stress fungal symbiosis K stress mine site rehabilitation mycorrhizal colonization plant biomass amendment plant nutrition water deficiency

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stable Isotopic Signatures of NO₃ in Waste Water Effluent and Los Angeles River

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Journal of Water Resource and Protection 2024年第1期16卷 102-122页

作者： Isaac hall Mohammad Hassan Rezaie Boroon Department of Geography Geology and Environment California State University Los Angeles California USA

A metropolitan city such as Los Angeles (LA) is an ideal study site with a very high population density, and it houses at least 3 treatment plants where sewage is treated preliminarily and then progressing to tertiary treatment before discharging into the LA River. We will gain a better understanding of the water quality in the LA River and the nitrate load in the watershed system by examining the influence of waste water treatment plants (WWTPs). The goal of this study is to pinpoint the exact source of nitrate in the LA River using the isotope signatures. We have selected sampling locations both upstream and downstream of the WWTP. This serves to monitor nitrate levels, aiding in the assessment of treatment plant effectiveness, pinpointing nitrate pollution sources, and ensuring compliance with environmental regulations. The research explores the isotopic composition of NO3 in relation to atmospheric nitrogen and Vienna standard Mean Ocean Water, shedding light on the contributions from various sources such as manure, sewage, soil organic nitrogen, and nitrogen fertilizers. Specifically, there is a change in the δ15NAir value between the dry and wet seasons. The isotope values in the Tillman WWTP sample changed between dry and wet seasons. Notably, the presence of nitrate originating from manure and sewage is consistent across seasons, emphasizing the significant impact of anthropogenic and agricultural activities on water quality. This investigation contributes to the broader understanding of nitrogen cycling in urban water bodies, particularly in the context of wastewater effluent discharge. The findings hold implications for water quality management and highlight the need for targeted interventions to mitigate the impact of nitrogen-containing compounds on aquatic ecosystems. Overall, the study provides a valuable framework for future research and environmental stewardship efforts aimed at preserving the health and sustainability of urban water resources. This

关键词： Metropolitan City Los Angeles Treatment Plants Sewage Treatment Nitrate Source Isotope Signatures Water Quality

SMILE soft X-ray Imager flight model CCD370 pre-flight device characterisation

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Earth and Planetary Physics 2024年第1期8卷 25-38页

作者： S.Parsons D.J.hall O.Hetherington T.W.Buggey T.Arnold M.W.J.Hubbard A.Holland Centre for Electronic Imaging the Open UniversityMilton KeynesMK76AAUK

Throughout the SMILE mission the satellite will be bombarded by radiation which gradually damages the focal plane devices and degrades their *** order to understand the changes of the CCD370s within the soft X-ray Imager,an initial characterisation of the devices has been carried out to give a baseline performance *** CCDs have been characterised,the two flight devices and the flight spa *** has been carried out at the Open University in a bespo ke cleanroom measure ment *** results show that there is a cluster of bright pixels in the flight spa re which increases in size with tempe *** at the nominal ope rating tempe rature(-120℃) it is within the procure ment ***,the devices meet the specifications when ope rating at -120℃ in 6 × 6 binned frame transfer science *** se rial charge transfer inefficiency degrades with temperature in full frame *** any charge losses are recovered when binning/frame transfer is implemented.

关键词： CCD soft X-ray imager characterisation SMILE

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面向电铲自主装卸的矿用自卸车斗型优化

吉林大学学报（工学版） 2024年第5期54卷 1227-1236页

作者：谭晓丹王勇澎 Robert hall 徐天爽黄庆学吉林大学机械与航空航天工程学院长春130022 太原重型机械集团有限公司矿山采掘装备及智能制造国家重点实验室太原030024 南达科他州矿业理工大学采矿工程与管理学院拉皮德城57701 太原理工大学机械与运载工程学院太原030024

针对现有电铲自主装卸功能在料堆重构、环境感知、目标识别等领域存在技术难度的现状,从降低自主装卸作业任务难度的角度出发,本文提出了一种以载荷均衡分布为目标的矿用自卸车斗型优化方法。首先,构建了一种基于差分迭代的装卸后自卸... 详细信息

针对现有电铲自主装卸功能在料堆重构、环境感知、目标识别等领域存在技术难度的现状,从降低自主装卸作业任务难度的角度出发,本文提出了一种以载荷均衡分布为目标的矿用自卸车斗型优化方法。首先,构建了一种基于差分迭代的装卸后自卸车斗内料堆的轮廓重构方法,并对料堆质心位置进行计算;其次,建立并验证了模拟电铲装卸过程的离散元仿真方法;再次,利用离散元仿真实验,研究了不同斗型结构参数对斗内料堆质心位置的影响;最后,以横向载荷均布为目标,以纵向载荷分布、行驶安全性、斗容变化为约束对斗型进行优化。结果表明:优化后的斗型与原斗型相比,在保持装载能力和行驶安全性的前提下,极端装卸位置时的载荷分布均匀性显著提升,并具有更大的合理装卸面积和更高的作业效率。

关键词：机械设计及理论自主装卸矿用自卸车载荷分布斗型优化

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Diesel engine exhaust exposures in two underground mines

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International Journal of Mining Science and Technology 2017年第4期27卷 641-645页

作者： Debia Maximilien Couture Caroline Njanga Pierre-Eric Neesham-Grenon Eve Lachapelle Guillaume Coulombe Hugo hallé stéphane Aubin Simon Department of Environmental and Occupational Health School of Public Health Universite de Montreal 2375 chemin de la Cote Ste-Catherine Montreal H3T IA8 Canada Department of Mechanical Engineering F.cole de Technologie Superieure 1100 rue Notre-Dame Ouest Montreal H3C 1K3 Canada Health and Safety Agnico Eagie Mines 145 King Street East Suite 400 Toronto MSC 2Y7 Canada Health and Safety Westwood Mine (IAMGOLD) Chemin Arthur Doyon PreissacJOY 2EO Canada Institut de recherche Robert-Sauve en sante et en securite du travail (IRSst) 505 Boul. de Maisonneuve Ouest Montreal H3A 3C2 Canada

Exposure to diesel engine exhaust(DE) is a major concern in underground mines. It has been linked to cardiopulmonary diseases and is classified as a human carcinogen. The goal of this study is to assess DE exposures in workers at two underground gold mines, to compare exposure levels within and between the mines, and to compare different methods of measuring DE exposures, namely respirable combustible dust(RCD), elemental carbon(EC) and total carbon(TC). Ambient and personal breathing zone(PBZ) measurements were taken. Side-by-side monitoring of RCD and of the respirable fraction of EC and TC(EC_Rand TC_R) was carried out in the workers' breathing zone during full-shift *** ambient measurements, in addition to EC_R, TC_Rand RCD, a submicron aerosol fraction(less than 1 mm) of EC and TC was also sampled(EC_1and TC_1). Average ambient results of 240 mg/m^3 in RCD, 150 mg/m^3 in EC_Rand 210 mg/m^3 in TC_Rare obtained. Average PBZ results of 190 mg/m^3 in RCD,84 mg/m^3 in EC3Rand 150 mg/min TC_Rare obtained. Very good correlation is found between EC_Rand EC_1 with a Pearson correlation coefficient of 0.99(p st exposures are reported for loadhaul-dump(LHD) and jumbo drill operators and conventional miners. Significant exposure differences are reported between mines for truck and LHD operators(p < 0.01). The average TC_R/EC_Rratio is 1.6 for PBZ results, and 1.3 for ambient results. The variability observed in the TC_R/EC_Rratio shows that interferences from non-diesel related organic carbon can skew the interpretation of results when relying only on TC data.

关键词： Diesel exposure Underground mine Respirable combustible dust Elemental carbon Total carbon Diesel particulate matter Similar exposure groups

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Rare Presentation of Meningioma as an External Auditory Canal Mass

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International Journal of Otolaryngology and Head & Neck Surgery 2024年第5期13卷 378-383页

作者： Justin hall Nikitha Jona Crescentia Cho Michele Gandolfi Department of Otolaryngology Atrium Health Wake Forest Baptist Health Winston Salem NC USA Department of Otolaryngology Wake Forest University School of Medicine Winston Salem NC USA

This is a case of a 60-year-old male with a history of prior left middle fossa meningioma that was partially resected with an operative report noting diffuse attachment to the middle fossa floor. Gamma knife was recommended but he never completed this management. He then presented about eight years later with a mass from his left external auditory canal. It was reported that two years prior another surgeon operated on the left ear for a cholesteatoma. CT temporal bone showed complete opacification of left EAC, mastoid bowl, and remaining mastoid air cells. In addition, there were irregular bony/hyperostotic changes seen within the left sphenoid and temporal bone. There was dural thickening within the middle fossa adjacent to the previously described hyperostotic bony changes. A mastoidectomy and excision of mass revealed extensive adhesive tissue throughout the middle ear, and mastoid up to the tegmen. Pathology of the portions that were resected confirmed Grade 1 meningioma. stereotactic gamma knife radiation was completed to the area to prevent further growth. This case highlights extracranial meningioma that did not have definitive management for prior middle fossa floor meningioma. It also highlights the need to think of less common pathology in the middle ear and external auditory canal.

关键词： Middle Ear Cranial Base Otology/Neurotology