Facetting value of helical thread surface received by enveloping

В морской технике применяются различные резьбовые соединения. Детали судовых механизмов подвергаются в процессе работы вибрациям и переменным нагрузкам, которые приводят их к разрушениям, потере герметичности и к внеплановым остановкам судовых машин.. Для повышения эксплуатационных свойств и увеличения срока службы резьбовых соединений проводят анализ качества сопрягаемых поверхностей, в частности, параметров шероховатости. В предлагаемой статье исследуется величина огранки винтовой поверхности резьбы образующаяся при осуществлении нового метода изготовления резьбы огибанием. Процесс обработки металла, к которому относится новый метод нарезания, заключается в касании лезвия инструмента и обрабатываемого материала прерывистым касанием. Нарезание резьбы осуществляется, специальной червячной фрезой. При прерывистом резании обрабатываемая поверхность оказывается, как бы составленной из отдельных криволинейных площадок (граней), Линия стыка граней имеет определенную высоту по нормали к поверхности, при нарезании резьбы - к винтовой поверхности. Высота стыка граней определяет качественный показатель шероховатости поверхности, называемый волнистостью. При нарезании резьбы червячной фрезой высота стыка граней (волнистость винтовой поверхности) зависит от числа зубьев фрезы. Задача исследования состоит в том, чтобы выяснить, каким должно быть число зубьев фрезы для получение заданной шероховатости винтовой поверхности резьбы и как это влияет на качество поверхности резьбы. Так же в статье рассмотрено графическое описание процесса получения огранки резьбы и пример расчета числа гребенок фрезы. There are many different thread joints used on marine facilities. While in operation, components of the mechanisms undergo vibrations with repeated stresses that leads to their failures, loss of tightness, and unscheduled shutdowns of the equipment. The analyses of joint surfaces quality, e.g. roughness parameters, are conducted to enhance serviceability of the thread joints and to prolong their lifespan. The article studies facetting value of a helical thread surface while applying a new method of thread production – enveloping. The new method of cutting that is a process of metal treatment involves non-continuous contacting an instrument blade and the material being cut. The cutting of the thread is done with a special hob cutter. Due to the non-continuous cutting, a treated surface becomes as if consisting of curved pads or faces. The faces junction line has a specific normal line level towards the surface and towards the helical surface during the cutting. The height of the junction defines qualitative indicator of the surface roughness known as undulation. When cutting the thread with a hob cutter the height of the faces junction - undulation of a helical surface – depends on a cutter teeth number. The research objective is to specify the cutter teeth number needed to achieve the required roughness of a thread helical surface as well as to determine how it influences on the quality of the thread surface. The paper also provides several drawings illustrating the process of obtaining the thread facetting and the example of calculation of a cutter chaser number.

Geometric Theorems and Application of the DOF Analysis of the Workpiece Based on the Constraint Normal Line

Aiming at the problem of judging the degree of freedom (DOF) of the workpiece in the fixture by experience, it is difficult to adapt to the analysis of the DOF of some singular workpieces. The workpiece and the fixture are used as rigid bodies, and the workpiece is allowed to move in the plane or space under the constraints of the fixture positioning point, and a set of geometric theorems for judging the DOF and overconstraint of the workpiece can be derived according to the difference in the position of the instantaneous center of the workpiece speed. The judgment of the DOF and overconstraint of the workpiece is abstracted into rules with universal meaning, which effectively overcomes the limitations of existing methods. The research results show that (1) the DOF and overconstraint of the workpiece in the fixture depend entirely on the number of positioning normal lines of the workpiece and their geometric relationship; (2) the necessary and sufficient condition for limiting the DOF of rotation of the workpiece around a certain axis is that the workpiece has a pair of parallel normal lines in the vertical plane of the axis. Using geometric theorems to judge the DOF of the workpiece is more rigorous, simple, and intuitive, which is convenient for computer-aided judgment and the reasonable layout of the positioning points of the workpiece, which can effectively avoid the misjudgment of the DOF and unnecessary overpositioning when the complex workpiece is combined and positioned on different surfaces. Several examples are used to verify the accuracy of the method and correct unreasonable positioning schemes.

Research on the Influence of External Parameters of Fan-Type Nozzle on Water Jet Performance

At present, high-pressure water jet technology occupies a very important position in the automobile washing industry. Some automatic washers cannot meet the washing requirements in the washing process due to unreasonable arrangement of nozzles on their spray rods. Based on the theory of computational fluid dynamics (CFD), the internal and external flow field model of the nozzle are established in this paper. Fluent is used to simulate and analyze the flow field, and the external parameters of the nozzle on the side spray bar of the automatic automobile washer are optimized. The simulation results show that after the nozzle and the normal line of the automobile surface are inclined at a certain angle, the target surface is affected not only by normal striking force but also by tangential pushing force, which makes stains easier to remove. The washing effect is the best when the nozzle is inclined 30° to the normal line of the automobile surface. Increasing the nozzle inlet pressure will increase the dynamic pressure on the automobile surface, but the increase of dynamic pressure will decrease after increasing to a certain pressure. The inlet pressure has little effect on the area covered by water jet. The reasonable matching results of jet angle, nozzle spacing, and nozzle distance from the automobile surface (target distance) obtained by numerical simulation can not only make the automobile surface completely covered and cleaned but also ensure less jet interference and no waste of water from adjacent nozzles. The above research conclusions can provide a basic theoretical basis for the optimal design of automatic automobile washing.

A Flow-Measuring Algorithm of Arc-Bottomed Open Channels through Multiple Characteristic Sensing Points of the Flow-Velocity Sensor in Agricultural Irrigation Areas

Precise flow measurement in the open channel is a key prerequisite to implementation of modern agricultural efficient water use. The channel with an arc-bottomed shape is the most common channel type in irrigation area at present. The paper has verified the log-law is along the normal line rather than along the vertical line in arc-bottom channel. By conducting the velocity distribution log-law, this paper derives the expression of the multiple characteristic sensing points location of the flow-velocity sensor in the channel section, which is along the normal line. Based on this, a new algorithm to estimate the discharge of the arc-bottomed channel flow is proposed. We have also developed the experiment of the arc-bottomed channels (including semicircular channels, arc-bottom trapezoidal channels and U-shaped channels) and utilize the data to verify the method. The results indicate that the sensing locations expression of the flow velocity measuring sensor such as acoustic doppler velocimetry and propeller is suitable for improving discharge estimation’s accuracy of the arc-bottomed channels. This method could be extensively used in estimating discharge of irrigation and drainage channels in agricultural water conservancy projects. It will enhance the efficiency and accuracy of water resources management departments in irrigation areas, which also meet the strategic requirements of agricultural sustainable development.

O Filósofo Experimentador

<p class="western" style="margin-bottom: 0cm; font-variant: normal; font-style: normal; font-weight: normal; line-height: 100%; text-decoration: none;" align="center"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;">A essência e a existência,</span></span></p><p class="western" style="margin-bottom: 0cm; font-variant: normal; font-style: normal; font-weight: normal; line-height: 100%; text-decoration: none;" align="center"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;">ora tessituras de um filósofo contemplador,</span></span></p><p class="western" style="margin-bottom: 0cm; font-variant: normal; font-style: normal; font-weight: normal; line-height: 100%; text-decoration: none;" align="center"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;">fulguraram em sua real potência</span></span></p><p class="western" style="margin-bottom: 0cm; font-variant: normal; font-style: normal; font-weight: normal; line-height: 100%; text-decoration: none;" align="center"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;">enunciando a razão de um sábio admirador.</span></span></p>

Visual contour tracking based on inner-contour model particle filter under complex background

In this paper, a novel particle filter–based visual contour tracking method is proposed, which uses inner-contour model to track contour object under complex background. The purpose is to achieve effectiveness and robustness against complex background. To that end, the proposed method first utilized Sobel edge detector to detect the edge information along the normal line of the contour. Then, it sampled the inner part of the normal line to get the local color information, which was then combined with the edge information to construct new normal line likelihood. After that, all the inner color information was used to construct global color likelihood. Finally, the edge information, local color information, and global color information were fused into new observation likelihood. Experimental results showed that the proposed method was robust for contours tracking under complex background, and it was also computationally efficient and can run in real-time completely.

Juventude, Cultura e Favela: projetos sociais entre políticas públicas de juventude e “pacificação”

<p class="western" style="text-indent: 1.3cm; margin-bottom: 0cm; font-weight: normal; line-height: 0.64cm;" lang="en-GB" align="JUSTIFY"><span style="color: #00000a;">O presente artigo analisa a produção da categoria “juventude” ao longo da trajetória das políticas públicas voltadas de juventude (PPJ) no Brasil e sua relação com modos de agenciamento e governo de jovens moradores(as) de espaços populares, como as favelas. Para tanto, parte de um breve histórico das PPJ em nível federal para refletir sobre a formulação de uma política pública que se delineia enquanto curso ou projeto social de cultura voltado para jovens moradores(as) de favelas pacificadas no Rio de Janeiro (onde haviam sido instaladas Unidades de Polícia Pacificadora) e as ideias e concepções sobre juventude e cultura mobilizadas em seus materiais e na narrativa de um de seus formuladores. </span></p>

Comparative Study of Research Project Supervision on the Performance of Graduating Business Students in Nigerian Universities

<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">Badanie miało na celu porównanie nadzoru nad projektem badawczym wśród studentów kończących<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> studia w Kwara State University (KWASU) i University of Ilorin (UNILORIN) przez dwie sesje. Nacisk<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> położono na ustalenie związku między czynnikami motywacyjnymi, czynnikami hamującymi, pracą<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> uczniów i możliwościami badawczymi. W badaniu wykorzystano projekt korelacji do ustalenia charakteru<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> relacji. Ujawniono istnienie istotnego związku między wyżej wymienionymi czynnikami a zarządzaniem<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> czasem przez studentów na obu uniwersytetach.</span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /></span>

Zastosowanie chmur obliczeniowych do organizacji pracy grupowej w czasie rzeczywistym

<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">Celem artykułu było uzasadnienie możliwości efektywnego wykorzystania chmur obliczeniowych<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> i oferowanych przez nie serwisów do organizowania pracy grupowej pracowników biurowych w czasie<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> rzeczywistym. W opracowaniu wskazano zalety zastosowania chmur obliczeniowych w zarządzaniu informacjami, określono obecny stan ich wykorzystania oraz uzasadniono korzyści i możliwości chmur<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> obliczeniowych w organizowaniu pracy z dokumentami w trybie online. We wnioskach zamieszczono<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> możliwe kierunki dalszych badań.</span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /></span>