检索结果-南通市图书馆

Natural convection effects on TNT solidification inside a shaped charge mold

Defence Technology（防务技术） 2022年第9期18卷 1653-1661页

作者： Cigdem Susantez aldelio b.caldeira bruna R.Loiola Trakya University Engineering FacultyMechanical Engineering DepartmentEdirne22030Turkey Management and Technological Innovation Agency Brazilian ArmyRio de Janeiro23020-470Brazil Military Institute of Engineering Mechanical Engineering DepartmentRio de Janeiro22290-270Brazil

High Explosive Anti-Tank(HEAT) warheads and ammunitions are frequently produced by explosive casting inside an axis-symmetric mold with an inverted conical geometry in the basis. In order to prevent manufacturing defects, the solidification process must be controlled. In this study, a dimensionless solidification model has been proposed to investigate the heat transfer considering the natural convection inside the liquid explosive and the numerical simulations were performed by using COMSOL Multiphysics and Modeling Software, employing trinitrotoluene(TNT) thermophysical properties. The effect of three different boundary conditions on the top of the mold have been evaluated: convection, adiabatic and isothermal. It has been observed that solidification process was faster for convection case and slower for isothermal case, while an intermediary total solidification time value was found for adiabatic case.Moreover, liquid explosive was completely surrounded by solid explosive during the solidification process for convection case and also for adiabatic case through the end of the process. Otherwise, it was not observed for isothermal case. The natural convection effects promoted a vortex inside the liquid explosive, accelerating the heat transfer process. It has been concluded that isothermal mold top boundary condition should be preferred to prevent manufacturing defects, avoiding high thermal stress.

关键词： Solidification Natural convection Explosive Dimensionless model Anti-Tank ammunition

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Plant growth and metabolism of exotic and native Crotalaria species for mine land rehabilitation in the Amazon

引用

Journal of Forestry Research 2024年第1期35卷 143-154页

作者： Hemelyn Soares das Chagas Rafael Silva Guedes Markus Gastauer Paula Godinho Ribeiro Allan Klynger da Silva Lobato Cecílio Frois caldeira Fabrício William deÁvila AndréRodrigues dos Reis Silvio Junio Ramos Instituto Tecnológico Vale Rua Boaventura da Silva955BelémPA 66055-090Brazil Universidade Federal do Sul e Sudeste do Pará XinguaraPABrazil Núcleo de Pesquisa Vegetal básica e Aplicada Universidade Federal Rural da AmazôniaParagominasPABrazil Departamento de Engenharia Florestal Universidade Estadual do Centro-Oeste/UNICENTROIratiPRBrazil School of Sciences and Engineering São Paulo State University(UNESP)TupãSP.CEP 17602-496Brazil

Despite its enormous benefits,mining is respon-sible for intense changes to vegetation and soil properties.Thus,after extraction,it is necessary to rehabilitate the mined areas,creating better conditions for the establishment of plant species which is challenging.This study evaluated mineral and organic fertilization on the growth,and carbon and nitrogen(N)metabolism of two Crotalaria species[Cro-talaria spectabilis(exotic species)and Crotalaria maypu-rensis(native species from Carajás Mineral Province(CMP)]established on a waste pile from an iron mine in CMP.A control(without fertilizer application)and six fertilization mixtures were tested(i=NPK;ii=NPK+micronutrients;iii=NPK+micronutrients+organic compost;iv=PK;v=PK+micronutrients;vi=PK+micronutrients+organic compost).Fertilization contributed to increased growth of both species,and treatments with NPK and micronutrients had the best results(up to 257%cf.controls),while organic fertilization did not show differences.Exotic Crotalaria had a greater number of nodules,higher nodule dry mass,chlorophyll a and b contents and showed free ammonium as the predominant N form,reflecting greater increments in biomass compared to native species.Although having lower growth,the use of this native species in the rehabilitation of mining areas should be considered,mainly because it has good development and meets current government legislation as an opportunity to restore local biodiversity.

关键词： biological nitrogen fixation Mining Nitrogen metabolism Plant nutrition

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Critical analysis of molluscicide application in schistosomiasis control programs in brazil

引用

Infectious Diseases of Poverty 2016年第1期5卷 485-490页

作者： PMZ Coelho RL caldeira Research group of Schistosoma mansoni biology and Its Interaction with the Host RenéRachou InstituteOswaldo Cruz Foundation-Minas Gerais30190-002 Belo HorizonteMGBrazil Research group of Medical Helminthology and Malacology RenéRachou InstituteOswaldo Cruz Foundation-Minas Gerais30190-002 Belo HorizonteMGBrazil

In brazil,biomphalaria glabrata,b.tenagophila,and b.straminea are naturally infected by the trematode Schistosoma mansoni,the causative agent of schistosomiasis.Despite decades of governmental efforts through official control programs,schistosomiasis remains an important public health problem in the country:thousands of people are infected with the trematode each year and millions live in endemic areas.The World Health Organization recommends using a combination of molluscicide(niclosamide)and mass chemotherapy to control the transmission of schistosomiasis,with this treatment successfully reducing the morbidity of the disease.In the past,niclosamide has been used in official schistosomiasis control programs in brazil.However,as b.glabrata recolonizes even after molluscicide application,the use of molluscicides has gradually decreased in the country until they were discontinued in 2002,mainly due to the rising global pressure to preserve the environment and the difficulties of obtaining licenses from the brazilian Ministry of Environment to use toxic substances in aquatic ecosystems.Therefore,the discovery of new molluscicides,which could be more selective to biomphalaria species and less harmful to the aquatic ecosystem,is necessary.In addition,political efforts to sensitize funders to provide grants for this field of research are required.In this context,this article aims to make a critical analysis of molluscicide application in schistosomiasis control programs in brazil.

关键词： biomphalaria Molluscicide Schistosoma mansoni Schistosomiasis Vector control braz

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Plant growth and nutrient use efficiency of two native Fabaceae species for mineland revegetation in the eastern Amazon

引用

Journal of Forestry Research 2020年第6期31卷 2287-2293页

作者： Silvio J.Ramos Markus Gastauer Simone K.Mitre Cecı´lio F.caldeira Joyce R.Silva Antonio E.Furtini Neto Guilherme Oliveira Pedro W.M.Souza Filho Jose´O.Siqueira Instituto Tecnolo´gico Vale Rua Boaventura da Silva955Belem 66055-090Brazil Departamento de Ciencia do Solo Universidade Federal de LavrasLavras 37200-000Brazil

The primary challenge of mineland revegetation is the establishment of species able to cope with low availability of nutrients,especially in steep slopes such as of mine pits.We evaluated plant growth response and nutrient use efficiency(NUE)of two promising native Fabaceae species(Dioclea apurensis—liana from metalliferous savannas;bauhinia longipedicellata—tree from Amazon rainforest)from the Caraja´s Mineral Province,eastern Amazon-brazil.Plants were grown separately in 2-kg pots filled with mining waste.Substrates were fertilized with nitrogen,phosphorus,potassium(NPK),lime,and micronutrients.The results showed increments on growth of both species when nutrients were applied to the mining waste.D.apurensis showed increases in leaf area,plant height,stem diameter,and shoot dry mass production when NPK or NPK?micronutrients were applied,while b.longipedicelata was responsive to application of NPK?lime or NPK?lime?micronutrients.Further,D.apurensis showed higher NUE than b.longipedicelata,especially at the lowest doses of N,P and K.These findings may indicate a substantial advantage of D.apurensis for mineland revegetation,as this species may require lower nutrient inputs,being,therefore,a more sustainable way to revegetate degraded areas.

关键词： Fertilizer application Mining soil Tropical forest Nutrient use efficiency

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Gas Exchange and Production of Photosynthetic Pigments of <i>Piper aduncum</i>L. Grown at Different Irradiances

引用

American Journal of Plant Sciences 2013年第12期4卷 114-121页

作者： Fernanda Ventorim Pacheco Helbert Rezende de Oliveira Silveira Amauri Alves Alvarenga Ivan caldeira Almeida Alvarenga José Eduardo brasil Pereira Pinto Jean Marcel Sousa Lira Departamento de Agricultura Geral UFLA-Universidade Federal de Lavras Lavras Brazil Setor de Fisiologia Vegetal Departamento de Biologia UFLA-Universidade Federal de Lavras Lavras Brasil

The species Piper aduncum is a plant with great economic potential, because the essential oil has antimicrobial activity and insecticides. Thus, as the light directly affects photosynthesis process, the present study evaluated the gas exchanges’ variables and photosynthetic pigments’ production of P. aduncum grown under different irradiances. Treatments consisted in environments with 100%, 70% and 50% of irradiance and environments with colored nets (red and blue). After 150 days of culture, photosynthetic activity (A), stomatal conductance (gs) transpiration rate (E), internal CO2 concentration (Ci), deficit vapor pressure (DVP), leaf temperature, concentration of internal/external CO2 (Ci/Ca), carboxylation efficiency (A/Ci) and efficiency water use (A/E) were evaluated. Pigments chlorophyll a, b, carotenoids, total and chlorophyll a/b ratio were also measured. From the observed data, it can be concluded that the species Piper aduncun developed various mechanisms for adaptation to different irradiance conditions. Moreover, it can be inferred that their photosynthetic process is more efficient and has larger spectral intensities of light, with higher efficiency photosynthetic when grown under 70% and 100% of radiation.

关键词： Long Pepper Color Nets Chlorophyll Luminosity Ecoambients

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：