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1.
在“碳达峰”、“碳中和”的目标背景下,绿色低碳、清洁高效成为资源开采的新要求,也对科学开采这一复杂系统问题的研究提出了新的方向。阐述了矿产资源开采理念的发展演化,综述了近年来国内外在科学开采方面的研究现状,构建了安全、高效、绿色、低碳、经济、科学管理“六位一体”的科学开采体系,丰富了科学开采的内涵和框架。从复杂科学问题的判断标准、科学开采体系的特征两方面进行推断,得出科学开采属于复杂问题,承载科学开采复杂问题的系统是复杂系统。以复杂科学的思路研究科学开采的复杂性,构建科学开采复杂系统模型,从顶层设计、中层连接和底层基础3个层次思考了实现科学开采的新途径,为实现矿产资源的科学开采提供了新的发展方向。  相似文献   

2.
Recognizing the pervasive importance of materials science and engineering (MSE) to practically every facet of man’s life, this lecture takes a broad view of the origin and technical trends and achievements in MSE, briefly reviewing its history and relationship to society over many millennia, to the present day, with specific examples. Major emphasis, however, is placed on modern MSE as related to current national issues, using as illustrations of the latter natural resources, industry and the economy, research and development, education, and technology transfer. The discussion of these areas leads to consideration of the role of the Federal Government and the importance of and need for a coherent national policy to deal with critical issues, many of which are listed herein. Some important steps by the Government fostering high level coordination as well as cooperation among government, industry, and academe are cited. Having thus illustrated the pervasive and vital impact of MSE on society, and its current esteemed recognition and position of influence, the lecture concludes that in this period of global change — social, economic, and technological — there is a challenge to MSE to respond beneficially to societal needs more than ever before. The opportunity and mechanisms now exist. Greater participation in the public and political arenas, with mutual education, is indicated. NATHAN E. PROMISEL received his Bachelor of Science and Master of Science Degree at the Massachusetts Institute of Technology, did his doctorate work at Yale University, and received an Honorary Doctor of Engineering Degree at Michigan Technological University. He became Assistant Lab Director at International Silver Company, leaving in 1940, and Chief Materials Scientist and Engineer (aeronautics and weapons) and Materials Research Coordinator for the Department of the Navy, leaving in 1966. He is presently an International Consultant. Dr. Promisel has been a long-time member of the National Materials Advisory Board of the National Academies of Science and Engineering, and from 1966 to 1974 was its Executive Director. He was also a Member of the Office of Technology Assessment (Congress) Materials Advisory Committee, as well as Chairman or Member of numerous other Government and public technical groups. These included being Chairman of the U.S. Group for the Science Exchange Program with the U.S.S.R., for materials and electrometallurgy, and serving as Chairman of the NATO Aerospace Research Group (Materials and Structures). Dr. Promisel is a member of the National Academy of Engineering; Past President, Fellow, and Honorary Member, American Society for Metals; Past President and Founding Member of the Federation of Materials Societies; Honorary Member of AIME, ASTM, and SAE (Materials Division); Fellow of British Institute of Metals and SAMPE. He has presented distinguished lectures to The Electrochemical Society and ASTM. Dr. Promisel has received numerous awards and is the holder of two patents. He has written 65 technical papers and has been the author, contributor, or editor of eight books.  相似文献   

3.
综述了近年来电解液的热稳定性影响因素、热失控过程及产物成分、单体及电池组燃爆安全性、灭火措施的研究进展.指出电解液的热稳定性受锂盐和有机溶剂的共同影响,当电池内部温度达到120℃左右时放热反应开始出现,在热量持续积累的情况下热失控将自发进行,同时产生氢气和烷烃类具有燃烧爆炸危险的气体产物.与二氧化碳和干粉类灭火剂相比,七氟丙烷和水的灭火效果较好.最后对锂离子电池的应用前景做了展望,提出了不同滥用条件下的热失控过程、热失控产物生成机理,指出开发新型电解液和寻求高效灭火介质是今后研究的方向.   相似文献   

4.
讨论了空间机械臂在轨插、拔孔操作的阻抗控制问题。为此,结合系统动量守恒关系,空间机械臂替换部件末端输出插、拔孔主动力与孔内所受摩擦阻力作用关系,以及第二类拉格朗日方程,推导得到了载体位置、姿态均不受控制情况下,空间机械臂在轨插、拔孔操作过程系统动力学方程。同时,根据相关操作控制系统设计需要,利用系统位置几何关系分析、建立了空间机械臂替换部件末端相对基联坐标系的相对运动雅可比关系。之后,由空间机械臂替换部件末端位姿与末端输出插、拔孔主动力之间的动态关系并结合阻抗控制原理,建立了二阶线性阻抗模型。在上述工作基础上,针对空间机械臂在轨插、拔孔操作过程同时存在运动学与动力学不确定性的情况,设计了空间机械臂替换部件末端力/位姿跟踪指数型阻抗控制策略;并通过李雅普诺夫理论,证明了控制系统的稳定性。提到的控制策略具有结构简单、收敛速度快、稳定性好的特点。系统数值仿真,验证了上述控制策略的有效性。   相似文献   

5.
OBJECTIVE: To identify issues related to the quality of health care in the United States, including its measurement, assessment, and improvement, requiring action by health care professionals or other constituencies in the public or private sectors. PARTICIPANTS: The National Roundtable on Health Care Quality, convened by the Institute of Medicine, a component of the National Academy of Sciences, comprised 20 representatives of the private and public sectors, practicing medicine and nursing, representing academia, business, consumer advocacy, and the health media, and including the heads of federal health programs. The roundtable met 6 times between February 1996 and January 1998. It explored ongoing, rapid changes in health care and the implications of these changes for the quality of health and health care in the United States. EVIDENCE: Roundtable members held discussions with a wide variety of experts, convened conferences, commissioned papers, and drew on their individual professional experience. CONSENSUS PROCESS: At the end of its deliberations, roundtable members reached consensus on the conclusions described in this article by a series of discussions at committee meetings and reviews of successive draft documents, the first of which was created by the listed authors and the Institute of Medicine project director. The drafts were revised following these discussions, and the final document was approved according to the formal report review procedures of the National Research Council of the National Academy of Sciences. CONCLUSIONS: The quality of health care can be precisely defined and measured with a degree of scientific accuracy comparable with that of most measures used in clinical medicine. Serious and widespread quality problems exist throughout American medicine. These problems, which may be classified as underuse, overuse, or misuse, occur in small and large communities alike, in all parts of the country, and with approximately equal frequency in managed care and fee-for-service systems of care. Very large numbers of Americans are harmed as a direct result. Quality of care is the problem, not managed care. Current efforts to improve will not succeed unless we undertake a major, systematic effort to overhaul how we deliver health care services, educate and train clinicians, and assess and improve quality.  相似文献   

6.
This work offers an overview of the state of the art and future state of environmental health in our country from a viewpoint of the impact of the commercial opening established in the Free Trade Agreement among Mexico, the USA, and Canada. In the first section of this work, we analyze the expected economic changes resulting from the implementation of the FTA and foretells the way in which those changes will influence the present environmental and epidemiologic profiles of this country in the medium and long term. The main changes predicted by the analysis are, in the epidemiologic context, the acceleration of the transference of occupational, consumption, environmental and population risks, characteristic of industrialized countries, to the country's polarized epidemiologic profile; and, in the environmental context, a transition consisting of a broadening and composition of the spectrum of pollutants, including and important lagging of bacteriologic control. The second section offers an analysis of the predicted response capacity facing the new environmental risk dynamics in the country, encompassing regulation, normativeness and enforcement of environmental and consumer protection, as well as obstacles found in health services to the implementation of surveillance, detection and treatment of health damages caused by environmental factors. The analysis of the organized social response to these problems discloses a relative flexibility of the normativeness and enforcement functions in comparison with our northern neighbors, a paramount factor for the possible transference of environmental risks, as well as the informational and research deficiency about environmental issues, basic elements for sustaining environmental health in the country, aiming at speeding up the development and transference of technologies for prevention, detection and management of environmental risks in the country, drawing upon the systematization of our experience and that of our neighbors. This speeding process ought to match, in the medium term, the velocity of risk transference produced by the commercial opening. In this way, the commercial integration of North America will become a favorable context for the development of the environmental health infrastructure of the country.  相似文献   

7.
The gene families encoding the immunoglobulin variable regions of heavy (VH) and light (VL) chains in vertebrates are composed of many genes. However, the gene number and the extent of diversity among VH and VL gene copies vary with species. To examine the causes of this variation and the evolutionary forces for these multigene families, we conducted a phylogenetic analysis of VH and VL genes from the species of amniotes. The results of our analysis showed that for each species, VH and VL genes have the same pattern of clustering in the trees, and, according to this clustering pattern, the species can be divided into two groups. In the first group of species (humans and mice), VH and VL genes were extensively intermingled with genes from other organisms; in the second group of species (chickens, rabbits, cattle, sheep, swine, and horses), the genes tended to form clusters within the same group of organisms. These results suggest that the VH and VL multigene families have evolved in the same fashion: they have undergone coordinated contraction and expansion of gene repertoires such that each group of organisms is characterized by a certain level of diversity of VH and VL genes. The extent of diversity among copies of VH and VL genes in each species is related to the mechanism of generation of antibody variety. In humans and mice, DNA rearrangement of immunoglobulin variable, diversity, and joining-segment genes is a main source of antibody diversity, whereas in chickens, rabbits, cattle, sheep, swine, and horses, somatic hypermutation and somatic gene conversion play important roles. The evolutionary pattern of VH and VL multigene families is consistent with the birth-and-death model of evolution, yet different levels of diversifying selection seem to operate in the VH and VL genes of these two groups of species.  相似文献   

8.
We studied the absorbing peripheral lymphatic vessel with the light microscope, the transmission electron microscope, the scanning electron microscope, and three-dimensional models of the diaphragm of several rodents and insectivores under normal and experimental conditions (lymphatic stasis and dehydration). To clarify the delicate and complex mechanism that permits drainage of the abdominal cavity contents into the lymphatic circulatory system, we introduced Polystyrene latex spherules, China ink, and Trypan blue into the abdominal cavities. After anatomical comparisons of the superficial and deep networks of absorbing peripheral lymphatic vessels at the tendinous and muscular portions of the diaphragm and after classification of lymphatic vessels into absorbing and conducting functions, we examined the stomata, which, owing to morphologic and topographic findings, we defined as stable structures. Furthermore, we observed that the stomata and submesothelial connective channel are fundamental elements that facilitate the flow of the corpuscular and liquid contents of the peritoneal cavity to the submesothelial absorbing lymphatic vessel wall. Also, we underlined that the genesis of the connective channel depends on the secondary cytoplasm extensions of two distinct adjacent endothelial cells, which, to facilitate the flow of the absorbed abdominal contents, completely coat this channel. Additionally, our observations illustrate that the secondary cytoplasm extensions do not engage in continuous relationships with the basal lamina of the mesothelium and with the margins of the stoma, and, hence, the hypothesis of "lymphatic stomata" as an expression of the anchoring of the borders of the open interendothelial junctions to the orifice margins of the stoma cannot be confirmed. Moreover, we describe the presence and formation of intraendothelial channels in the lymphatic endothelial wall. We affirm that this morphological entity is a dynamic unit, because its numerical density varies according to different physiological and experimental conditions to degrees of hydrostatic and colloidal osmotic pressure and, perhaps, also to the particular characteristics of the substances that the connective channel liberates into the endothelial wall of the lymphatic vessel. In conclusion, we affirm that the absorbing peripheral lymphatic vessels of the diaphragm, by way of intraendothelial channel formations, membrane diffusion, and the vesicular path of the endothelial cells, constitute the fundamental draining elements for the corpuscular and liquid contents of the abdominal cavity.  相似文献   

9.
推进矿山绿色开采是一项长期而复杂的系统工程,而绿色开采技术的应用面临着投资周期长和成本高等问题,鉴于此,开展绿色开采技术优先级评价,有助于指导矿山决策部门的工作,实现绿色开采有序化,降低投资成本。在构建三山岛金矿绿色开采技术体系的基础上,提出了一种灰色关联分析优化模型,并利用该模型对绿色开采技术进行评价分析。首先,构建了层次化绿色开采技术评价指标体系,系统地反映了各因素对绿色开采技术的影响;然后,利用AHP法和熵值法组合赋权,弥补了主观赋权法和客观赋权法的不足,使赋权趋于合理化;最后,分别应用3种赋权方法的优化模型和传统等权法模型对三山岛金矿绿色开采技术的绿色度进行量化分析,并对比分析了4种模型的关联度计算结果,最终得出三山岛金矿绿色开采技术推进的优先级。  相似文献   

10.
对非洲中南部某镍矿石的工艺矿物学特征进行研究,为合理有效利用该镍矿石提供依据,采用X射线荧光光谱分析、多元素分析、X射线衍射和镜下鉴定等方法,分析了矿石的化学成分、矿物组成、嵌布特征、矿石结构构造以及主要金属矿物磁黄铁矿和镍黄铁矿的嵌布粒度等。研究结果表明:该矿石中镍含量高达3.42%,以镍黄铁矿的形式存在;硫化镍矿嵌布粒度较粗,+150 μm粒级含量为38.20%,+75 μm粒级含量达68.58%,但分布不均匀。该矿石镍品位高且含镍矿物嵌布粒度相对较粗,属于易选矿石类型,白云石、滑石等含镁脉石矿物的存在是影响该镍矿分选的主要因素。  相似文献   

11.
The antigenic and allergenic chemical analysis of spore and mycelia extracts of Pisolithus tinctorius was carried out. The spores were collected from basidiocarps in plantations of Eucalyptus spp and the mycelia from culture in MNM medium. With basis on the fungus growth curve, the mycelia masses were obtained after 10, 20, 30, and 40 days of incubation, which correspond, respectively, to the beginning, middle and end of the log phase, and beginning of the decline phase. The mycelia masses, together with the spores, were submitted to the action of three extractors (Coca, Tris-HCl, and ammonium bicarbonate). The contents of carbohydrates and proteins were determined. The SDS-PAGE electrophoretical analysis revealed separate fractions in these extracts, besides common fractions, in function of cultivation time and extraction methods. The selected extracts for the allergic tests were the ones with the highest number of fractions. The prick-tests were conducted in 374 patients--rural workers, eucalyptus plantation workers, and college students. The positivity to the "prick test" with the antigenic extract of P. tinctorius was, respectively, 3.78%, 28.20% and 6.40%. Most prick-test positive patients (82.75%) also presented symptoms of respiratory allergy (asthma and rhinitis). There was no reactivity difference when the spore and mycelia extracts were employed. The analysis of the positive patients' sera revealed the presence of IgE specific to the P. tinctorius antigens. Since Pisolithus tinctorius is found as mycorrhiza of Eucalyptus spp, and this plant is used in reforestation in most countries, the importance of that fungus should be regarded as a possible cause of respiratory allergies, especially in occupationally exposed workers.  相似文献   

12.
唐伟  陶桂林  王兴东  孔建益  王紫阳  李震 《钢铁》2021,56(10):99-107
 某薄取向硅钢复卷线采用了恒张力收卷方案,卸卷后无芯筒料卷约有5%的概率发生心形坍塌,经济损失严重。为了研究心形卷产生机理及影响因素,降低坍塌几率,基于弹性力学叠加原理,建立了料卷收卷-卸卷的连续内应力分布模型;进一步基于压力埋管理论分析了无芯筒薄料卷心形坍塌过程,确定了坍塌区层数;测量了12组带厚为0.23、0.283 mm的心形卷的屈曲半圆心角与屈曲区层数,测量值与理论预测值基本吻合,验证了所提理论的准确性。分析了钢带厚度和粗糙度、橡胶层等效径向刚度对内应力的影响。研究表明,随钢带厚度和粗糙度、橡胶层等效径向刚度的减少,料卷心形坍塌概率及坍塌层数增大;该规律与现场观察一致。通过减小橡胶层厚度、增加橡胶层弹性模量可增大等效径向刚度,大幅减小料卷压应力,降低心形坍塌概率和坍塌区层数。  相似文献   

13.
为了研究钢铁制造流程耗散结构的本质及其特征,以高炉炼铁区段为对象,研究解析了多工序协同动态运行条件下的耗散结构优化问题.由料场、焦化、烧结、球团、高炉等工序所组成的炼铁区段,不仅是钢铁制造流程中重要的物质/能源转换中心,也是全流程动态有序、协同连续运行的关键和基础环节.炼铁区段的物理本质是铁素物质流在碳素能量流的驱动和...  相似文献   

14.
以添加Ni前后的Fe-Cu合金和Fe-Cu-Ni合金为研究对象,采用金相显微镜(OM)观察了Fe-Cu合金与Fe-Cu-Ni合金时效过程中的显微组织形貌变化,借助硬度测试分析了两种合金在等温时效过程中的硬度变化规律,并利用透射电子显微技术(TEM)进行了两种合金的析出相精细结构观察与衍射分析,在此基础上,通过实验与理论...  相似文献   

15.
The Medical Sciences School of the University of Santiago de Chile, is an institution inserted in the occidental culture and therefore on its conceptions and traditions. It subscribes the Principles defined in the Universal Declaration of the Human Rights of the United Nations and especially the importance of the human person, as an entity irrepetible, different to others. The human rights are over the institutions, the society and the laws of science. The Faculty considers the family as the cell or natural and fundamental element for the development of the human being in the society. It defines its historic mission as the search of the truth and the achievement of a society in pro of the welfare and health of the people in a frame of excellence, justice, humanism, efficiency and participation. As an expression of the cultural patrimony it should create and transfer knowledge. As guarantor of the ethical principles it should protect the dignity that emanates from the transcendent nature of the person and its moral principles and therefore its right to life, justice, freedom, equality, health, education, and happiness. As a paradigm of progress it must be involved in modernization and should impulse the development. As an entity committed with Society it should participate in the search of solutions for politics and programs looking for a higher level of life and a better model of health. The profile of our graduated students will identify them due to their profound spirit of welfare of the person, his family, his community, ethical sense, solidarity, justness and humanity, their orientation to the community and the environment with a solid professional formation in the strategy of Primary Health Care. They will provide education in health for the whole family in order to improve a better way of life. They will be trained to detect and solve the risks of individual, communities and environment. Research is also a priority of the Faculty in order to contribute to solve the problems of health of the Nation, since there is no development without education and there is no education neither development without health. For the Faculty the achievement of these purposes is mandatory and we will make them reality through the Prometeo Project 1997-2001.  相似文献   

16.
For counseling settings, research suggests that softness, personalization, and order might affect the experience and the perceived expertness, trustworthiness, and social attractiveness of the therapist. This article discusses exploratory studies on college students' perception of the counseling office environment and whether the likely client experience was associated with the softness/personalization and order of the office. As stimuli, the studies used 30 color photographs of psychotherapists' offices viewed from the client's perspective. After obtaining ratings of the characteristics of each office, we obtained ratings from different groups of students of the quality of care and comfort expected in each office (Study 1) and how qualified, bold, and friendly the therapist in the office would be (Study 2). Additional studies examined the likelihood of choosing a therapist based on the office, and the first thought or feeling that came to mind about the office, the therapist, and the patient experience. There were strong correlations in response between groups (by whether they had experienced therapy; their level in school; their gender; and their major, location, and school size). The quality of care, comfort, therapist boldness, qualifications of the therapist, and the likelihood that one would choose a therapist based on the office improved with increases in the office's softness/personalization and order. Friendliness improved with increases in softness/personalization. The office choices, open-ended responses, and reported reasons for the ratings confirmed the importance of softness (comfort) and order. Research should test longer term exposure and behavior. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   

17.
A one-minute examination of the placenta performed in the delivery room provides information that may be important to the care of both mother and infant. The findings of this assessment should be documented in the delivery records. During the examination, the size, shape, consistency and completeness of the placenta should be determined, and the presence of accessory lobes, placental infarcts, hemorrhage, tumors and nodules should be noted. The umbilical cord should be assessed for length, insertion, number of vessels, thromboses, knots and the presence of Wharton's jelly. The color, luster and odor of the fetal membranes should be evaluated, and the membranes should be examined for the presence of large (velamentous) vessels. Tissue may be retained because of abnormal lobation of the placenta or because of placenta accreta, placenta increta or placenta percreta. Numerous common and uncommon findings of the placenta, umbilical cord and membranes are associated with abnormal fetal development and perinatal morbidity. The placenta should be submitted for pathologic evaluation if an abnormality is detected or certain indications are present.  相似文献   

18.
张晗  朱志明 《工程科学学报》2022,44(6):1002-1013
在对摩擦焊接进行分类并简要说明的基础上,对连续驱动摩擦焊接技术的研究发展和应用现状进行了全面梳理和深入剖析,涉及焊接工艺过程特征和主要工艺参数、工艺探索及工艺参数对接头性能的影响、数值分析和模拟及工艺参数优化、异种金属和非金属材料摩擦焊接与工艺创新、实际工程应用和焊接设备等方面。从摩擦焊接技术的潜在应用、核心科学问题、新型摩擦焊接设备的研发、数值分析和模拟、与新兴技术的结合等方面,对连续驱动摩擦焊接技术进行了评述和探讨。   相似文献   

19.
Human remains recovered from aquatic environments were scored for regional presence of soft tissue, exposure of bone, and loss of body parts to determine the general pattern of soft tissue loss and loss of body parts. Regions scored were: the cranium, mandible, neck, hands, forearms, upper arms, feet, legs, pelvic girdle, and trunk. Initial disappearance of soft tissue, resulting in exposure of underlying bones, occurred in areas thinly overlain by soft tissue beginning with the head, hands, and anterior lower legs. Disappearance of body parts followed the general sequence: bones of the hands and wrists, bones of the feet and ankles, and the mandible and cranium. The lower legs, forearms, and upper arms are the next units to separate from the body. Known postmortem intervals for remains analyzed ranged from weeks to years and could not reliably be estimated based on the condition of the body at the time of recovery. As parts drop away from a floating carcass in large or current-driven bodies of water, they are often separated from the major body unit. This complicates recovery. Knowledge of disarticulation sequences allows more informed assessment of skeletal element recoveries to be expected and assists in the interpretation of artifacts and events produced by different disarticulating environments.  相似文献   

20.
为给回转窑工业试验提供参数,以小型试验最佳结果为基础,进行了高磷鲕状铁矿煤基直接还原?磁选提铁降磷扩大试验。结果表明,在最佳的条件下可获得铁品位94.17%、铁回收率77.47%以及磷质量分数0.08%的粉末还原铁,推荐的回转窑工业试验初始条件为:石灰石用量(质量分数)28%、无烟煤用量(质量分数)16%、还原温度1300 ℃,还原时间3 h。采用XRD以及SEM-EDS研究了无烟煤的作用机理,发现无烟煤用量增加,促进了浮氏体、镁铁尖晶石的还原以及铁颗粒长大,从而提高了铁的回收效果,但过多的无烟煤通过增强还原气氛及其带入的灰分消耗了石灰石,使铁矿物中的磷以及磷灰石还原成单质磷并与铁颗粒形成铁磷合金。   相似文献   

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