Application of Variational Geometry to the Analysis of Mechanical Tolerances

Author(s):  
P. M. Martino ◽  
G. A. Gabriele

Abstract The proper selection of tolerances is an important part of mechanical design that can have a significant impact on the cost and quality of the final product. Yet, despite their importance, current techniques for tolerance design are rather primitive and often based on experience and trial and error. Better tolerance design methods have been proposed but are seldom used because of the difficulty in formulating the necessary design equations for practical problems. In this paper we propose a technique for the automatic formulation of the design equations, or design functions, which is based on the use of solid models and variational geometry. A prototype system has been developed which can model conventional and statistical tolernaces, and a limited set of geometric tolerances. The prototype system is limited to the modeling of single parts, but can perform both a worst case analysis and a statistical analysis. Results on several simple parts with known characteristics are presented which demonstrate the accuracy of the system and the types of analysis it can perform. The paper concludes with a discussion of extensions to the prototype system to a broader range of geometry and the handling of assemblies.

Jurnal IPTA ◽  
2018 ◽  
Vol 6 (2) ◽  
pp. 124
Author(s):  
Syukriyan Abrar Syah ◽  
Ni Gusti Ayu Susrami Dewi ◽  
Putu Agus Wikanatha Sagita

This research aims to analyze factors affecting the satisfaction of tourists in the use of marine transportation from Bali toward Gili Trawangan. The benefits of this research useful to the company in improving the services for tourists who will use the services of a crosswalk leading to Gili Trawangan.The respondents in this research totalled 190 respondents, the selection of the sample using the method of purposive sampling, the data in this study were analyzed using the analysis factors that help by statistikal program SPSS version 17.0 for windows. The results of this study are: 1) the satisfaction of tourists in the use of sea transport in general are at a level of satisfaction. 2) there are three factors that affect the satisfaction of tourists formed i.e. factors quality of maids, the cost factor & ease factors and product quality. Quality of service factor is the most dominant factor influencing the satisfaction of travellers with variable reliability as the dominant variables, and the variable availability schedule is a variable that must be improved.


2021 ◽  
Vol 292 ◽  
pp. 02029
Author(s):  
Fei Lei ◽  
Liangmei Luo ◽  
Hang Yang ◽  
Qinhui Li ◽  
Feng Chen

This paper designs a survey questionnaire based on the Guangdong-Hong Kong-Macao Greater Bay Area’s demand for talents in international trade, adds job types, filters through package features, and performs feature filtering with the error filter criteria set in this paper, and conducts logistic regression analysis on talent types, so as to realize the classification and dynamic analysis of talents. The dynamic needs of various types of talents in international trade in the Guangdong-Hong Kong-Macao Greater Bay Area are drawn, and specific measures such as increasing salaries and benefits, reducing living costs, providing housing subsidies, solving children's employment problems, and ensuring quality of life are proposed for the development of international trade talents. Reducing the cost of talent migration can promote them to make more contributions to the Guangdong-Hong Kong-Macao Greater Bay Area. This will help the Guangdong-Hong Kong-Macao Greater Bay Area government to attract outstanding international trade talents and formulate detailed and feasible strategies, which has certain reference significance.


2007 ◽  
Vol Vol. 9 no. 1 (Distributed Computing and...) ◽  
Author(s):  
Pascale Minet ◽  
Steven Martin ◽  
Leila Azouz Saidane ◽  
Skander Azzaz

Distributed Computing and Networking International audience In this paper, we focus on applications having quantitative QoS (Quality of Service) requirements on their end-to-end response time (or jitter). We propose a solution allowing the coexistence of two types of quantitative QoS garantees, deterministic and probabilistic, while providing a high resource utilization. Our solution combines the advantages of the deterministic approach and the probabilistic one. The deterministic approach is based on a worst case analysis. The probabilistic approach uses a mathematical model to obtain the probability that the response time exceeds a given value. We assume that flows are scheduled according to non-preemptive FP/FIFO. The packet with the highest fixed priority is scheduled first. If two packets share the same priority, the packet arrived first is scheduled first. We make no particular assumption concerning the flow priority and the nature of the QoS guarantee requested by the flow. An admission control derived from these results is then proposed, allowing each flow to receive a quantitative QoS guarantee adapted to its QoS requirements. An example illustrates the merits of the coexistence of deterministic and probabilistic QoS guarantees.


Author(s):  
Michał Dereziński ◽  
Rajiv Khanna ◽  
Michael W. Mahoney

The Column Subset Selection Problem (CSSP) and the Nystrom method are among the leading tools for constructing interpretable low-rank approximations of large datasets by selecting a small but representative set of features or instances. A fundamental question in this area is: what is the cost of this interpretability, i.e., how well can a data subset of size k compete with the best rank k approximation? We develop techniques which exploit spectral properties of the data matrix to obtain improved approximation guarantees which go beyond the standard worst-case analysis. Our approach leads to significantly better bounds for datasets with known rates of singular value decay, e.g., polynomial or exponential decay. Our analysis also reveals an intriguing phenomenon: the cost of interpretability as a function of k may exhibit multiple peaks and valleys, which we call a multiple-descent curve. A lower bound we establish shows that this behavior is not an artifact of our analysis, but rather it is an inherent property of the CSSP and Nystrom tasks. Finally, using the example of a radial basis function (RBF) kernel, we show that both our improved bounds and the multiple-descent curve can be observed on real datasets simply by varying the RBF parameter.


2013 ◽  
Vol 10 (4) ◽  
pp. 1-38
Author(s):  
Dieter Schuller ◽  
Ulrich Lampe ◽  
Julian Eckert ◽  
Ralf Steinmetz ◽  
Stefan Schulte

The challenge of optimally selecting services from a set of functionally appropriate ones under Quality of Service (QoS) constraints – the Service Selection Problem – has been extensively addressed in the literature based on deterministic parameters. In practice, however, Quality of Service QoS parameters rather follow a stochastic distribution. In the work at hand, we present an integrated approach which addresses the Service Selection Problem for complex structured as well as unstructured workflows in conjunction with stochastic Quality of Service parameters. Accounting for penalty cost which accrue due to Quality of Service violations, we perform a worst-case analysis as opposed to an average-case analysis aiming at avoiding additional penalties. Although considering conservative computations, QoS violations due to stochastic QoS behavior still may occur resulting in potentially severe penalties. Our proposed approach reduces this impact of stochastic QoS behavior on total cost significantly.


1997 ◽  
Vol 119 (4A) ◽  
pp. 603-610 ◽  
Author(s):  
Chang-Xue (Jack) Feng ◽  
A. Kusiak

The quality loss function incorporates the cost of tolerances, however, it does not consider the manufacturing cost and design constraints. In this paper, a stochastic integer programming (SIP) approach is presented for simultaneous selection of tolerances and manufacturing processes. A direct link between the minimum manufacturing cost and the required level of manufacturing yield is established through the process capability index Cpk. As the tolerances in SIP are discrete, the solution generated is acceptable for manufacturing. It is shown that the integer programming models are applicable in the quality loss function and six sigma design approaches. The SIP approach is illustrated with a classical example of nonlinear tolerance design. The comparison of the proposed SIP approach, the Taguchi method, and the conventional mathematical models in tolerance synthesis is presented.


2021 ◽  
Vol 3 (1) ◽  
pp. 099-103
Author(s):  
M. V. Vasina ◽  
◽  
A. S. GOLYSH ◽  
K. V. TROFIMENKO ◽  
◽  
...  

This work consists of the characteristics of production, assessment of the qualitative and quantitative composition of water, consideration of the process of water purification in the chemical shop, comparison and selection of coagulants and flocculants, and demonstration of the most affordable technology used at the CHPP which increases the efficiency of source water purification. The problem of pretreatment of the source water has always been relevant. The quality of the water used depends on the operation of boilers and turbines at the CHPP. The paper presents the average annual indicators of the quality of the source water, pre-treatment methods, and considers which reagents that do not require the cost of reconstruction of clarifiers can improve their performance. The initial water after the application of the test samples of coagulants and flocculants was studied. Conclusions are drawn about the work of clarifiers after the use of the proposed reagents.


2019 ◽  
Vol 140 ◽  
pp. 04018
Author(s):  
Olga Gamayunova ◽  
Anton Radaev ◽  
Mikhail Petrichenko ◽  
Raimond Bogdanivics

In the market of building materials today there is a large selection of various thermal insulation materials, differing in cost, thermal conductivity and other characteristics. This article describes the predictive model of the cost of insulation from thermal characteristics, such as: thickness, thermal conductivity, (average) density, water absorption and combustibility group. The coefficient of determination was used to assess the quality of the obtained economic-mathematical model. The described predictive model can be effectively used to solve problems associated with determining the optimal characteristics of insulation by the criterion of minimizing cost.


2019 ◽  
pp. 62-65
Author(s):  
K.N. Tishaninov ◽  
A.V. Anashkin

Зерноочистительные агрегаты зачастую используют поточные технологические линии для послеуборочной очистки зерна, от качества работы которых зависит стоимость конечного продукта и рентабельность всего цикла производства зерна. Разделение потока зерна на две технологические линии происходит с использованием тройника зернопровода, что приводит к перегруженности одной линии и недогруженности другой. Зерноочистительные машины работают за рамками рекомендуемых нагрузок, что приводит к низкому качеству очистки и высокому уровню потерь зерна. Для качественной настройки зерноочистительных машин в составе технологии послеуборочной очистки зерна необходимы устройства для разделения потоков зерна. В ФГБНУ ВНИИТиН разработаны несколько классов авторегулируемых устройств (делителей): с грузовоспринимающей системой, с щелевыми отверстиями и т.д. Нами рассматривается одно из таких устройств делитель потока зерна с горизонтальным размещением щелевых отверстий. Теоретически обоснована взаимосвязь погрешности деления в зависимости от асимметричности подачи зерна в стабилизирующей ёмкости, высоты насыпи, ширины отводящих каналов. Показана кривая распределения погрешности разделения в зависимости от отклонений подачи зерна по ширине и длине ёмкости. На основе теоретического анализа сформулированы рекомендации по технологической настройке и выбору оптимальных конструктивных параметров каскадного делителя.Grain cleaning units often use flow lines for postharvesting cleaning of grain, the quality of work which depends on the cost of the final product and the profitability of the entire cycle of grain production. The separation of the grain flow into two production lines occurs using the tee of the grain pipe which leads to congestion of one line and underloading of the other. Grain cleaning machines operate beyond the recommended loads which lead to poor cleaning quality and high levels of grain loss. For highquality setting of grain cleaning machines as part of the technology of postharvesting cleaning of grain, devices for the separation of grain flows are needed. Several classes of automaticallycontrolled devices (dividers): with a loadperceived system, with slotted openings, etc. are developed in FSBSI AllRussian Scientific Research Institute for the Use of Machinery and Oil Products in Agriculture. One of these devices a grain flow divider with horizontal placement of slotted openings is considered by us. Theoretically, the relationship between the error of division depending on the asymmetry of the grain supply in a stabilizing tank, the height of the embankment, the width of the discharge channels. The distribution curve of separation error is shown depending on the deviations of the grain feed across the width and length of the tank. Based on the theoretical analysis recommendations for technological adjustment and selection of optimal part specifications of a cascade divider are formulated.


2000 ◽  
Vol 8 (3) ◽  
pp. 291-309 ◽  
Author(s):  
Alberto Bertoni ◽  
Marco Carpentieri ◽  
Paola Campadelli ◽  
Giuliano Grossi

In this paper, a genetic model based on the operations of recombination and mutation is studied and applied to combinatorial optimization problems. Results are: The equations of the deterministic dynamics in the thermodynamic limit (infinite populations) are derived and, for a sufficiently small mutation rate, the attractors are characterized; A general approximation algorithm for combinatorial optimization problems is designed. The algorithm is applied to the Max Ek-Sat problem, and the quality of the solution is analyzed. It is proved to be optimal for k≥3 with respect to the worst case analysis; for Max E3-Sat the average case performances are experimentally compared with other optimization techniques.


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