952 resultados para vacuum-pump


Relevância:

100.00% 100.00%

Publicador:

Resumo:

The possibility to install a getter vacuum pump and its feasible in the anode of a high-power klystron amplifier is investigated in order to decrease of the pressure in the gun and consequently increasing its lifetime. The study is conducted using a 1.3 GHz, 100 A and 240 kV high-power klystron with five reentrant coaxial cavities, assembled in a cylindrical drift tube 1.2 m long. This work takes into account the specific conductance of components of gun and all important gas sources, like the degassing of the drift tube, the cavity walls, the cathode, the anode, and the collector, as well the position and pumping speed of the getter vacuum pump in anode region. © 2006 IEEE.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Negative-pressure therapy or vacuum-assisted closure (VAC) has been used in clinical applications since the 1940’s and has increased in popularity over the past decade. This dressing technique consists of an open cell foam dressing put into the wound cavity, a vacuum pump produces a negative pressure and an adhesive drape. A controlled sub atmospheric pressure from 75 to 150 mmHg is applied. The vacuum-assisted closure has been applied by many clinicians to chronic wounds in humans; however it cannot be used as a replacement for surgical debridement. The initial treatment for every contaminated wound should be the necrosectomy. The VAC therapy has a complementary function and the range of its indications includes pressure sores, stasis ulcers, chronic wounds such as diabetic foot ulcers, post traumatic and post operative wounds, infected wounds such as necrotizing fasciitis or sternal wounds, soft-tissue injuries, bone exposed injuries, abdominal open wounds and for securing a skin graft. We describe our experience with the VAC dressing used to manage acute and chronic wounds in a series of 135 patients, with excellent results together with satisfaction of the patients.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The interest in the development of climbing robots has grown rapidly in the last years. Climbing robots are useful devices that can be adopted in a variety of applications, such as maintenance and inspection in the process and construction industries. These systems are mainly adopted in places where direct access by a human operator is very expensive, because of the need for scaffolding, or very dangerous, due to the presence of an hostile environment. The main motivations are to increase the operation efficiency, by eliminating the costly assembly of scaffolding, or to protect human health and safety in hazardous tasks. Several climbing robots have already been developed, and other are under development, for applications ranging from cleaning to inspection of difficult to reach constructions. A wall climbing robot should not only be light, but also have large payload, so that it may reduce excessive adhesion forces and carry instrumentations during navigation. These machines should be capable of travelling over different types of surfaces, with different inclinations, such as floors, walls, or ceilings, and to walk between such surfaces (Elliot et al. (2006); Sattar et al. (2002)). Furthermore, they should be able of adapting and reconfiguring for various environment conditions and to be self-contained. Up to now, considerable research was devoted to these machines and various types of experimental models were already proposed (according to Chen et al. (2006), over 200 prototypes aimed at such applications had been developed in the world by the year 2006). However, we have to notice that the application of climbing robots is still limited. Apart from a couple successful industrialized products, most are only prototypes and few of them can be found in common use due to unsatisfactory performance in on-site tests (regarding aspects such as their speed, cost and reliability). Chen et al. (2006) present the main design problems affecting the system performance of climbing robots and also suggest solutions to these problems. The major two issues in the design of wall climbing robots are their locomotion and adhesion methods. With respect to the locomotion type, four types are often considered: the crawler, the wheeled, the legged and the propulsion robots. Although the crawler type is able to move relatively faster, it is not adequate to be applied in rough environments. On the other hand, the legged type easily copes with obstacles found in the environment, whereas generally its speed is lower and requires complex control systems. Regarding the adhesion to the surface, the robots should be able to produce a secure gripping force using a light-weight mechanism. The adhesion method is generally classified into four groups: suction force, magnetic, gripping to the surface and thrust force type. Nevertheless, recently new methods for assuring the adhesion, based in biological findings, were proposed. The vacuum type principle is light and easy to control though it presents the problem of supplying compressed air. An alternative, with costs in terms of weight, is the adoption of a vacuum pump. The magnetic type principle implies heavy actuators and is used only for ferromagnetic surfaces. The thrust force type robots make use of the forces developed by thrusters to adhere to the surfaces, but are used in very restricted and specific applications. Bearing these facts in mind, this chapter presents a survey of different applications and technologies adopted for the implementation of climbing robots locomotion and adhesion to surfaces, focusing on the new technologies that are recently being developed to fulfill these objectives. The chapter is organized as follows. Section two presents several applications of climbing robots. Sections three and four present the main locomotion principles, and the main "conventional" technologies for adhering to surfaces, respectively. Section five describes recent biological inspired technologies for robot adhesion to surfaces. Section six introduces several new architectures for climbing robots. Finally, section seven outlines the main conclusions.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Os robots de movimentação de chapa são bastantes úteis para as empresas de metalomecânica. De facto, cada vez mais existem máquinas de corte por jato de água, laser ou outros processos, nos quais os robots apresentam um papel importante na carga e descarga do material. O trabalho realizado apresenta novas soluções aos sistemas de movimentação existentes no mercado, e permite reduzir os custos na movimentação do material. Este projeto serve essencialmente para chapas em trajetória retilínea, e efetuar o seu levantamento do equipamento e deposição em estrutura de suporte (ou viceversa). A vantagem a ter em conta é a diminuição dos custos de movimentação do material. Neste trabalho apresentou-se a metodologia de dimensionamento de um robot automatizado que transporta chapas com um peso máximo de 3500 kg, tendo por base as normas do EC3-P1.8 e o Método de Elementos Finitos (MEF). No decurso do projeto foram abordadas os seguintes temas: Abordagem inicial da geometria através do Solidworks; Dimensionamento da estrutura por software de Elementos Finitos, o Solidworks; Dimensionamento das correntes, carretos/discos ou coroas e rolamentos; Dimensionamento e seleção dos moto-redutores, bomba de vácuo e ventosas; Cálculo das solicitações em cada membro da estrutura por software de análise estrutural, o Multiframe3D, e respetivo dimensionamento das ligações aparafusadas e soldadas; Elaboração dos desenhos de projeto finais, processos de fabrico e custos; Dimensionamento do acionamento, MG e disposição dos dispositivos no quadro elétrico. Como conclusão refere-se que se conseguiu realizar o projeto e obter uma solução final otimizada, com a ajuda de ferramentas importantes, como sejam o MEF, resultando num equipamento cujas solicitações para a estrutura e sistema de movimentação foram otimizadas, resultando num equipamento eficiente, robusto, seguro e de custo reduzido.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Tässä diplomityössä käsitellään erikoispumppujen korjausprosessia teollisuuspumppujen korjauksiin erikoistuneessa konepajassa. Työn pääasiallinen tarkoitus on tuotantoprosessin kehittäminen ja tuotantovaiheiden esitteleminen. Tavoitteen taustalla on pyrkimys entisestään parantaa palvelukykyä ja asiakastyytyväisyyttä.Kolme eri keinoa päätavoitteen saavuttamiseksi ovat tuotannon suunnittelun ja ohjauksen kehittäminen, työssä käsiteltyjen pumpputyyppien korjausprosessien läpäisyaikojen lyhentäminen sekä korjausvaiheiden määrittely ja esittely vaihe vaiheelta. Työssä käsiteltyjä erikoispumpputyyppejä ovat imupumput, monijaksopumput sekä pysty/potkuripumput.Tuotannonsuunnittelun ja -ohjauksen kehittämiseksi sekä läpäisyaikojen lyhentämiseksi työssä etsittiin vaihtoehtoisia toimintatapoja. Kolmas tavoite, eli korjausvaiheiden määrittely, toteutettiin esittelemällä korjausprosessin vaiheet käsitellyillä pumpputyypeillä.Tuloksena saatiin keinoja tuotannon suunnittelun ja hallinnan kehittämiseksi. Useimmat keinot koskevat toimintatapojen selkiyttämistä. Myös keinoja läpäisyaikojen lyhentämiseksi löydettiin. Tietyllä imupumpputyypillä ja -koolla läpäisyajan lyheneminen oli 25 % ja osalla monijaksopumpuista jopa 75 %. Tulokset saavutetaan varastoimalla tiettyjä komponentteja, joilla on pitkä valmistus- tai korjausaika. Pysty/potkuripumppujen korjauksen läpäisyaikaa ei saatu lyhennettyä työn rajausten puitteissa Näiden tulosten lisäksi korjausprosessin toimintatavat määriteltiin.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Distillation is a unit operation of process industry, which is used to separate a liquid mixture into two or more products and to concentrate liquid mixtures. A drawback of the distillation is its high energy consumption. An increase in energy and raw material prices has led to seeking ways to improve the energy efficiency of distillation. In this Master's Thesis, these ways are studied in connection with the concentration of hydrogen peroxide at the Solvay Voikkaa Plant. The aim of this thesis is to improve the energy efficiency of the concentration of the Voikkaa Plant. The work includes a review of hydrogen peroxide and its manufacturing. In addition, the fundamentals of distillation and its energy efficiency are reviewed. An energy analysis of the concentration unit of Solvay Voikkaa Plant is presented in the process development study part. It consists of the current and past information of energy and utility consumptions, balances, and costs. After that, the potential ways to improve the energy efficiency of the distillation unit at the factory are considered and their feasibility is evaluated technically and economically. Finally, proposals to improve the energy efficiency are suggested. Advanced process control, heat integration and energy efficient equipment are the most potential ways to carry out the energy efficient improvements of the concentration at the Solvay Voikkaa factory. Optimization of the reflux flow and the temperatures of the overhead condensers can offer immediate savings in the energy and utility costs without investments. Replacing the steam ejector system with a vacuum pump would result in savings of tens of thousands of euros per year. The heat pump solutions, such as utilizing a mechanical vapor recompression or thermal vapor recompression, are not feasible due to the high investment costs and long pay back times.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Alipainekiteytyksessä tasalaatuisen lopputuotteen valmistamiseksi kiteytysolosuhteiden vaikutus liuottimen haihtumisvuohon ja kiteiden ominaisuuksiin on huomioitava. Kandidaatin työn tavoitteena oli selvittää, miten glysiinin alipainekiteytyksessä vesiliuoksesta kiteytysolosuhteet (lämpötila ja paine) vaikuttavat liuottimen haihtumisvuohon ja syntyvien kiteiden polymorfiaan. Haihdutuskokeet suoritettiin puhtaalle vedelle ja alipainekiteytyskokeet glysiinin 95 % kylläiselle vesiliuokselle lämpötiloissa 40 °C, 50 °C ja 60 °C ja paineissa 40 mbar, 60 mbar ja 80 mbar. Kiteyttimenä käytettiin suljettua, virtaushaitoilla, sekoittimella ja ohjausputkella varustettua reaktoria johon oli kytketty alipainepumppu ja termostaatti paineen ja lämpötilan ohjaamiseksi. Nesteen määrä haihdutuskokeissa oli 2 kg ja alipainekiteytyskokeissa 1,2 kg. Osa alipainekiteytyskokeista saaduista kiteistä analysoitiin jauheröntgendiffraktioanalysaattorin (PXRD, engl. powder x-ray diffraction) avulla. Kaikki PXRD-laitteella analysoidut alipainekiteytyskokeissa saadut kiteet osoittautuivat glysiinin γ-polymorfiksi. Kiteytysolosuhteilla oli selkeä vaikutus haihtumisvuohon, mutta vaikutusta glysiinikiteiden polymorfiaan ei havaittu koealueella.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Sugar cane juice or garapa darkens quickly after extraction due to the oxidation of some of its constituents harming its commercialization thus requiring rapid consumption. The objective of this study was to develop a mild process for sugar cane clarification, obtaining a cloudy, greenish-yellow beverage. The following parameters were combined to aiming at this objective: heat treatment at 65 ºC/50 minutes; pH change (to 7.0, 7.5, and 8.0); addition of flocculant (0, 30, and 60 ppm Aluminum polychloride or APC - "Panclar P-1010"), and clarifier aid (0, 2, or 4 ppm of positively charged polyelectrolyte - "Magnafloc LT-27"). The decantation time was 45 minutes and the supernatant liquid was removed with a vacuum pump. The treatments were defined using the Response Surface Methodology and were submitted to physicochemical analysis for turbidity (%), total polysaccharide content (µg.mL-1), dextran content (µg.mL-1), and sensory analysis (acceptance test) for the attributes of color, appearance, and turbidity. It was concluded that the addition of 60 ppm APC, pH 8, and 0 ppm polyelectrolyte represented the best treatment to obtain a low polysaccharide content, 90% turbidity, and high scores for color, appearance, and turbidity. The beverage was sensorially well accepted by consumers.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

A study was made to compare dry matter, crude protein and gross energy digestibility of corn silage, associated to concentrate, through in vitro and in vivo digestion techniques. A completely randomized design was used, with two treatments and nine replications, involving three assays. The in vivo digestion assay was conducted with 12 Holstein heifers, on a 24 h permanent sample collection. The in vitro digestion assay was achieved with three collection methods: manual (M), vacuum pump (VP) and nasoesophagic (N). The collection methods VP and M can he used to determine the dry matter digestibility, instead of in vivo method, for the present study ration. The digestion methods influenced the DM, CP and GE digestibility for the studied ration.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

O uso de cápsulas porosas para extração de solução do solo é interessante por ser um ensaio não-destrutivo. Entretanto, persistem dúvidas sobre a liberação de íons da própria cápsula, que podem contaminar a solução extraída. Foram realizados testes na Faculdade de Ciências Agronômicas/UNESP, Botucatu (SP), com o objetivo de verificar a liberação de Ca e de Mg por cápsulas porosas de porcelana. No primeiro, foram empregados quatro tratamentos: T1 - lavagem das cápsulas com água destilada, forçando sua passagem pelas cápsulas, utilizando uma bomba a vácuo; T2 - lavagem das cápsulas com HCl 0,1 mol L-1, forçando sua passagem pelas cápsulas, utilizando uma bomba a vácuo; T3 - lavagem das cápsulas com água destilada, sem vácuo, e T4 - lavagem das cápsulas com HCl 0,1 mol L-1, sem vácuo, em um tempo de imersão de 24 h (para T3 e T4). No segundo teste, as cápsulas tratadas com HCl 0,1 mol L-1 no primeiro teste foram lavadas com água destilada novamente e deixadas de molho em água destilada e deionizada durante 45 min. Após estes procedimentos, as cápsulas foram imersas em água destilada, tomando-se alícotas desta solução para determinação de pH e dos teores de Ca e Mg após contato com as cápsulas por 0; 0,5; 1,0; 2,0; 4,0 e 24 h. Cada tratamento teve quatro repetições. Não se observou liberação significativa de Ca e Mg das cápsulas porosas para a solução, quando foram preparadas utilizando-se da passagem de HCl 0,1 mol L-1 a vácuo e água destilada, e deixadas, a seguir, em água destilada e deionizada durante 4 h.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

This investigation was carried out within the Parana sedimentary basin, Brazil, involved the sampling of effluents and groundwater from monitoring stations situated at different sites at São Paulo State, and was realized with the purpose of evaluating the presence of fats, oil and grease (FOG) in different matrices. Several tests were realized with very distinct materials (cooking oil, butter, margarine, pig fat, vacuum pump oil) in order to properly calibrate the spectrophotometric system. Each matrix was dissolved with 1,1,1-trichloroethane and from the stock solutions it was prepared working standards from different dilutions. The data obtained were plotted on absorbance vs. concentration graph that yielded a successful calibration curve when a mineral oil for vacuum pump was utilized in the experiments at a wavelength corresponding to 410 mn. The results obtained for the analyzed samples were compared with the limiting value established by the São Paulo State legislation on the prevention and pollution control of the environment that was established in 8(th) September 1976 by Rule No. 8468.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Estudou-se o efeito de três métodos de coleta (manual, bomba a vácuo e sonda nasoesofageana) sobre os teores de ácidos graxos voláteis totais (AGVt), nitrogênio amoniacal e número de protozoários no fluido ruminal de bovino. Utilizou-se o delineamento inteiramente casualizado, com três tratamentos e cinco repetições. Os resultados revelaram que o método da sonda nasoesofageana proporcionou valores menores dos ácidos propiônico, butírico, AGVt e de nitrogênio amoniacal no fluido ruminal. O número total de protozoários não foi afetado pelos métodos de coleta de conteúdo ruminal. O método de coleta manual e por meio de bomba a vácuo mostraram-se eficientes para os parâmetros estudados.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The pressure field in a high-power klystron amplifier is investigated to scale the ionic vacuum pump used to maintain the ultra high-vacuum in the device in order to increase its life-time. The investigation is conducted using an 1.3 GHz, 100 A - 240 keV high-power klystron with five reentrant coaxial cavities, assembled in a cylindrical drift tube 1.2 m long. The diffusion equation is solved to the regime molecular flow to obtain the pressure profile along the axis of the klystron drift tube. The model, solved by both analytical and numerical procedures, is able to determine the pressure values in steady-state case. This work considers the specific conductance and all important gas sources, as in the degassing of the drift tube and cavities walls, cathode, and collector. For the drift tube degassing rate equals to q(deg) = 2x10(-12) (-)mbar.L.s(-1) cm(-2) (degassing rate per unit area), to cavities q(cavity) = 3x10(-13) mbar.L.s(-1)cm(-2), to the cathode q(cathode) = 6x10(-9)_mbar.L.s(-1) and to the collector q(collector) = 6x10(-9) mbar.L.s(-1), it was found that a 10 L.s(-1) ionic vacuum pump connected in the output waveguide wall is suitable. In this case, the pressure obtained in the cathode is p(cathode) = 6.3x10(-9) mbar, in the collector p(collector) = 2.7x10(-9) mbar, and in the output waveguide p = 2.1x10(-9) mbar. Although only the steady-state case is analyzed, some aspects that may be relevant in a transient situation, for instance, when the beam hits the drift tube walls, producing a gas burst, is also commented.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The purpose of this study was to observe the quality of seal of the glass ionomer cement, Ketac-Endo, after treatment of the root canal wall. The root canals of 140 extracted human teeth were prepared biomechanically. The root canals were treated with either EDTA or received an intracanal dressing of calcium hydroxide or camphorated paramonochlorphenol. The root canals were filled by the lateral condensation technique with gutta-percha points and the sealer Ketac-Endo, or zinc oxide-eugenol cement or Sealapex. The teeth were placed into a 2% methylene blue dye solution inside a flask, which was attached to a vacuum pump. Leakage was measured linearly. Sealapex exhibited significantly less leakage than Ketac-Endo or zinc oxide-eugenol cement (P<0.01). The use of EDTA and intermediary dressings reduced significantly (P<0.01) the leakage observed with the zinc oxide-eugenol sealer and Ketac-Endo.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The purpose of this study was to analyse the apical leakage in teeth filled by the lateral condensation technique following medication with calcium hydroxide. One hundred and twenty extracted human teeth were biomechanically prepared by using exclusively reaming motion with files up to #40. Half of the teeth received a calcium hydroxide dressing for 3 days. The medication was removed by irrigation and reaming motion with files #40 up to #70. The teeth were divided in 6 experimental groups, according to the dimension of the utilized instrument. The root canals were filled and posteriorly the teeth were placed into a 2% methylene blue dye solution inside a flask, which was attached to a vacuum pump. Leakage was measured linearly, and the results showed significantly (p<0.01) less leakage in the experimental groups that received calcium hydroxide dressings than in the control groups. The results persisted even after the removal of 300 micrometers of dentin from the root canal dentinal walls.