Brownian dynamics of rigid particles in an incompressible fluctuating fluid by a meshfree method

A meshfree Lagrangian method for the fluctuating hydrodynamic equations (FHEs) with fluid-structure interactions is presented. Brownian motion of the particle is investigated by direct numerical simulation of the fluctuating hydrodynamic equations. In this framework a bidirectional coupling has been introduced between the fluctuating fluid and the solid object. The force governing the motion of the solid object is solely due to the surrounding fluid particles. Since a meshfree formulation is used, the method can be extended to many real applications involving complex fluid flows. A three-dimensional implementation is presented. In particular, we observe the short and long-time behaviour of the velocity autocorrelation function (VACF) of Brownian particles and compare it with the analytical expression. Moreover, the Stokes-Einstein relation is reproduced to ensure the correct long-time behaviour of Brownian dynamics.Comment: 24 pages, 2 figure

FAKTOR RISIKO LINGKUNGAN PADA KEJADIAN PENYAKIT ASMA DI WILAYAH KERJA PUSKESMAS MANGKANG KOTA SEMARANG

Asma di Kota Semarang mengalami kenaikan jumlah dari tahun 2013 berjumlah 5040 kasus menjadi 5711 kasus pada tahun 2014. Prevalensi penyakit asma di Puskesmas Mangkang Kota Semarang sebesar 1,5% dengan jumlah kasus tahun 2014 dan 2015 sebanyak 117 dan 133 kasus. Selain adanya riwayat asma dalam keluarga, adanya partikulat pencemar udara juga berkontribusi terhadap timbulnya asma. Jenis partikulat diantaranya PM10 dan PM2,5. Partikulat pencemar udara di dalam rumah juga dipengaruhi kondisi fisik rumah. Penelitian ini bertujuan untuk mengetahui hubungan faktor risiko lingkungan dengan kejadian asma di wilayah kerja Puskesmas Mangkang Kota Semarang. Penelitian ini menggunakan jenis penelitian analitik observasional dengan desain penelitian case control. Besar sampel pada masing masing kelompok kasus dan kontrol sama yaitu 37 responden. Sampel pada kelompok kasus merupakan pasien yang didiagnosis menderita asma yang berobat di Puskesmas Mangkang Kota Semarang pada bulan November 2015-April 2016. Analisis data menggunakan analisis univariat dan bivariat dengan uji Chi Square. Rata rata suhu udara adalah 31 derajat Celcius, kelembaban udara 65%, dan konsentrasi PM10 585µg/m3. Hasil penelitian menunjukkan dari 8 variabel bebas yang diteliti terdapat 2 variabel yang berhubungan dengan kejadian asma yaitu kelembaban udara dalam rumah (p-value= 0,048; OR= 3,96; 95% CI= 1,140-13,756) dan keberadaan hewan peliharaan berbulu (p-value= 0,036; OR= 2,70; 95% CI= 1,056-6,941). Kesimpulan dari penelitian ini faktor risiko yang berhubungan dengan kejadian asma di Wilayah Kerja Puskesmas Mangkang Kota Semarang adalah kelembaban udara dalam rumah dan keberadaan hewan peliharaan. Kata Kunci: Asma, PM10, Pencemaran Udara, Semaran

Respiratory symptoms and chronic obstructive pulmonary disease : prevalence and risk factors in a predominantly low-income urban area of Cape Town, South Africa

Includes bibliographical references.The continuing worldwide increase in the incidence of chronic obstructive pulmonary disease (COPD) has led to international initiatives to improve surveillance and identify preventable risk factors for this and related chronic lung diseases. The studies reported here aimed to examine the prevalence and risk factors for respiratory symptoms and COPD; to introduce and test surveillance methodologies; and to inform treatment and control measures for this disease. The Lung Health Survey 2002 sampled 3512 individuals aged ≥ 15 years from an urban population of 36,334 in the predominantly low-income area of Ravensmead and Uitsig, Cape Town, South Africa. Information on respiratory symptoms, risk factors and healthcare utilisation was collected using a respiratory questionnaire which included questions that had been validated elsewhere. In 2005, a subsample of 960 persons aged ≥ 40 years participated in the Burden of Obstructive Lung Disease (BOLD) study comprised of a questionnaire and pre and postbronchodilator spirometry, in order to assess the prevalence of COPD. A high prevalence of respiratory symptoms of 38.3% was reported. Tobacco smoking showed a consistent positive association with chronic bronchitis, wheeze, dyspnoea and cough. Strong associations with cannabis smoking, pulmonary tuberculosis, occupational exposures and low socioeconomic status were found. The association of cannabis smoking with respiratory symptoms suggest that it may be a risk factor for COPD. The BOLD study revealed an exceptionally high prevalence of COPD in both men and women aged 40 years and older (29% and 20%, respectively) reflecting the very high prevalence of smoking in both sexes in the test area. The majority of those affected had moderate to severe disease, that is, symptoms with spirometric impairment (GOLD Stage II and higher). Even non-smoking women had a comparatively high prevalence of CO PO (12.6%), attributable to other risk factors such as tuberculosis and occupational exposures. Previous pulmonary tuberculosis was shown to be a strong predictor of COPD, which warrants further study. Review of healthcare utilisation confirmed significant under-recognition and under-treatment within local health services. These results confirm the need to prioritise preventative and treatment strategies for obstructive lung disease in South Africa

Deposition and characterization of magnetron sputtered BCC tantalum

The goal of this thesis was to provide scientific and technical research results for developing and characterizing tantalum (Ta) coatings on steel substrates deposited by DC magnetron sputtering. Deposition of tantalum on steel is of special interest for the protection it offers to surfaces, e.g. the surfaces of gun barrels against the erosive wear of hot propellant gases and the mechanical damage caused by the motion of launching projectiles. Electro-plated chromium is presently most commonly used for this purpose; however, it is considered to be carcinogenic in its hexavalent form. Tantalum is being investigated as non-toxic alternative to chromium and also because of its superior protective properties in these extreme environments. DC magnetron sputtering was chosen for this investigation of tantalum coatings on steel substrates because it is a versatile industrial proven process for deposition of metals. Sputter deposited Ta films can have two crystallographic structures: 1) body center cubic (bcc) phase, characterized by high toughness and high ductility and 2) a tetragonal beta phase characterized by brittleness and a tendency to fail under stress. It was found in this work that the bcc Ta coatings on steel can be obtained reliably by either of two methods: 1) depositing Ta on a submicron, stoichiometric TaN seed layer reactively sputtered on unheated steel and 2) depositing Ta directly on steel heated above a critical temperature. For argon sputtering gas this critical temperature was found to be 400°C at a pressure of 5 mtorr. With the heavier krypton gas, this critical temperature is reduced to 350°C. X-ray diffraction (XRD) was used to investigate the structure of tantalum and nitride films, and the composition of the nitride films was measured by nuclear reaction analyses (NRA), which were used to study in detail the enhancement of the bcc phase of Ta on steel. The scratch adhesion tests performed with a diamond hemispherical tip of radius 200 µm under increasing loads revealed high critical load values for failure (\u3e15 N) for the bcc coatings versus the low load values (\u3c9 N) for the beta coatings. The coating deposited on TaN interlayers on sputter-etched steel had better adhesion than those on steel surface without sputter etching. The results for this work have demonstrated that by controlling the various process parameters of dc magnetron sputtering, high quality bcc Ta coatings of multimicron thickness with excellent adhesion to steel can be made. An important contribution of this dissertation is in the enhancing an understanding of this process. The impact of this research will be in a number of fields where superior protective castings are needed. These include military applications, electronic components, chemical processing, and others

An Interactive Visual Approach to Construction Project Scheduling

Sound project management is an important pillar of success for a construction company. Project schedules are the primary tools for communicating the thinking and planning by the management team to all the stakeholders in a construction project. Traditional project scheduling software have become an indispensable tool for managers in various project oriented industries for tracking the schedule, the budget and resource requirements of a project as well as for preparing reports, providing on-line access to project information and communication with the members of the project team. However, these benefits are realized only after the project information is entered into the computer and updated periodically. Setting up a computer schedule for a construction project requires entering into the computer not only all project activities and their durations and resource requirements but also organizing and sequencing of project activities. This requires considerable time and effort and consequently a full-scale time study is not usually performed for all projects. New parametric CAD software is revolutionizing the way architects, engineers and contractors work and can significantly increase construction management productivity by substantially reducing the manual work necessary for computerized construction scheduling. The data model of new parametric CAD software allows easy exchange of building design information among various software systems during design, construction and service life of projects. Research is underway at Marquette University to investigate how new parametric CAD software such as Autodesk Revit can improve construction scheduling and project control functions. The main objective of the research is to find a simple and intuitive way for transferring the necessary project information from an architectural CAD model to scheduling software and streamlining sequencing and organizing project activities. Achieving this objective will eliminate one of the most tedious and time consuming steps in creating a construction project schedule. The study proposes a visual approach to extracting project information and transferring them to scheduling software. In this approach, first a 3D model of the project is created using project\u27s digital Revit CAD files. Extraction, organizing, sequencing and transferring of project elements to scheduling software is performed during a walkthrough of the 3D model. During a walkthrough, the user can select a building element by pointing to the element. This capability allows the user to select both an element and its predecessors before executing a command that sends the information to the scheduling program. This approach reduces the tedious task of listing, organizing, sequencing, and transferring construction project information to scheduling software to a simple expedition inside the building