Concept Of Envelope Research Articles

Model of Inverse Envelope Cutter with Ring-Involute Tooth

The design of a conical cutter is important in the manufacture of concave and convex gears. An inverse method is presented for determining the mathematical model of a rack cutter. The obtained rack cutter was used to generate concave and convex gears. The method proposed in this paper addressed design problems in the rack cutter that were used to generate a new type of concave and convex gears. Based on the two-parameter family of surfaces and direct envelope method, the conical cutter was used as the generating tool for the proposed gear type, and a mathematical model of gears with ring-involute teeth was developed according to gear theory. The contour of von-Mises stress distribution of the gear and the pinion of the proposed mathematical model is presented. Using CNC manufacturing technology, a gear with ring-involute teeth was manufactured by a conical cutter. Based on the inverse envelope concept, the mathematical model of the developed gear tooth was used to determine the geometrical and mathematical models of the rack cutter with ring-involute teeth. To illustrate the effectiveness of the method, a numerical example is presented to demonstrate the geometric model of a gear with a gear ratio of 3:2.

An efficient column generation design method of p-cycle-based protected working capacity envelope

The protected working capacity envelope (PWCE) concept was proposed by Grover (2004) in order to simplify network operations and management in survivable wavelength division multiplexing (WDM) networks. In this paper, we focus on the design of PCWE and investigate a new design method based on column generation (CG) for designing survivable WDM networks based on p-cycle PWCE. Proposed design algorithms for PWCE and p-cycle proceed in two steps: A first step where a large (sometimes huge) number of cycles is enumerated followed by a second step where the selection of the most promising p-cycles is made with the help of combinatorial optimization tools. In this paper, we develop a new (single-step) method based on large scale optimization tools, that is, CG techniques, where the generation of cycles is dynamic and embedded within the optimization process. The key advantage of CG techniques is that no a priori cycle enumeration step is required ahead of the optimization process: The generation of the relevant cycles, only one or few at a time, is embedded in the optimization process. We conducted intensive computational experiments to compare the performances of our CG algorithms with four other algorithms in the literature. The different algorithms were compared with regard to several design metrics and running time. Results obtained in the experiments on five different network instances show that the CG-based algorithm outperforms by far all proposed algorithms in the literature, both with respect to the scalability (much smaller computing times for large network instances) and also with respect to the quality of the solutions.

A theoretical envelope for internal instability of cohesionless soil

The nature of seepage-induced internal stability is characterised with reference both to effective stress in the finer fraction of the grain size distribution curve, and also to hydraulic gradient within the soil. The concept of a hydromechanical envelope is proposed in stress-gradient space. The onset of instability is triggered by a critical value of hydraulic gradient that is found consistent with the observations of Terzaghi on ‘piping' in uniform sand, and the observations of Skempton and Brogan on ‘segregation piping' in widely graded sandy gravels. The envelope takes the form of a linear relation that, for a particular soil, is governed by the proportion of effective stress in the finer fraction of soil grains.

Optimal stopping with dynamic variational preferences

We solve optimal stopping problems in uncertain environments for agents assessing utility by virtue of dynamic variational preferences as in Maccheroni, Marinacci and Rustichini (2006) [16] or, equivalently, assessing risk in terms of dynamic convex risk measures as in Cheridito, Delbaen and Kupper (2006) [4]. The solution is achieved by generalizing the approach in Riedel (2009) [21] introducing the concept of variational supermartingales and variational Snell envelopes with an accompanying theory. To illustrate results, we consider prominent examples: dynamic multiplier preferences and a dynamic version of generalized average value at risk introduced in Cheridito and Tianhui (2009) [5].

Ground Motion Synthesis Based on Power Spectrum Envelope

The paper proposes a new method, which is used for providing ground motion input for seismic design under rare earthquake action. The crucial step of this method is to use power spectrum envelop, obtained from natural earthquake records but not deriving from response spectrum, as target curve to synthesis ground motion. The result shows that power spectrum obtained from this method fits well with the target curve, and the produced ground motion can properly predict the response spectrum of acceleration. By importing the concept of energy envelope, this method reduces the randomness of the ground motion sampling and the variability of the result in dynamic finite element analysis.

Salud Mental y Comunicación Masiva

This article analizes to what extent Mental Health and Mass-Media are connected nowadays, The concept of Mental Health today envelopes ali aspects of individual' s life. The role of Mass-Media in our culture can not be ignored, in particular with regards to children. It is necessary to create regulatory mechanisms to promote Mental Health to-ali audiences through government and non government institutions.

Analysis of five- and six-machine micro-factory layouts for micro-pump productivity improvement

In the present study, analyses of two micro-factory layouts were performed to improve its micro-pump production rate and efficiency. For the purpose of the analysis, the two layouts, Layout A (existing) with five micro machines (including one micro milling machine) and Layout B (proposed) with six micro machines (including two micro milling machines), were constructed in the virtual environment. First, Layout A was simulated to predict the production time and to calculate the production rate and efficiency. The robot-arm waiting time, which was considered as the bottleneck, had a significant effect on the production rate. Second, to alleviate this bottleneck, we introduced, based on the robot-arm reach envelope concept, another micro milling machine to the Layout A, and named this new scheme Layout B. In the results of our analysis, Layout B improved the production rate by about 1.88 times and enhanced the efficiency by a factor of 1.57.

The end of the opportunism vs trust debate: Bounded reliability as a new envelope concept in research on MNE governance

Modern transaction cost economics (TCE) thinking has developed into a key intellectual foundation of international business (IB) research, but the Williamsonian version has faced substantial criticism for adopting the behavioral assumption of opportunism. In this paper we assess both the opportunism concept and existing alternatives such as trust within the context of IB research, especially work on multinational enterprise (MNE) governance. Case analyses of nine global MNEs illustrate an alternative to the opportunism assumption that captures more fully the mechanisms underlying failed commitments inside the MNE. As a substitute for the often-criticized assumption of opportunism, we propose the envelope concept of bounded reliability (BRel), an assumption that represents more accurately and more completely the reasons for failed commitments, without invalidating the other critical assumption in conventional TCE (and internalization theory) thinking, namely the widely accepted envelope concept of bounded rationality (BRat). Bounded reliability as an envelope concept includes two main components, within the context of global MNE management: opportunism as intentional deceit, and benevolent preference reversal. The implications for IB research of adopting the bounded reliability concept are far reaching, as this concept may increase the legitimacy of comparative institutional analysis in the social sciences.

Toward the Design of Mutation‐Resistant Enzyme Inhibitors: Further Evaluation of the Substrate Envelope Hypothesis

Previous studies have shown the usefulness of the substrate envelope concept in the analysis and prediction of drug resistance profiles for human immunodeficiency virus protease mutants. This study tests its applicability to several other therapeutic targets: Abl kinase, chitinase, thymidylate synthase, dihydrofolate reductase, and neuraminidase. For the targets where many (> or =6) mutation data are available to compute the average mutation sensitivity of inhibitors, the total volume of an inhibitor molecule that projects outside the substrate envelope V(out), is found to correlate with average mutation sensitivity. Analysis of a locally computed volume suggests that the same correlation would hold for the other targets, if more extensive mutation data sets were available. It is concluded that the substrate envelope concept offers a promising and easily implemented computational tool for the design of drugs that will tend to resist mutations. Software implementing these calculations is provided with the 'Supporting Information'.

Review on thermal performance of phase change energy storage building envelope

Improving the thermal performance of building envelope is an important way to save building energy consumption. The phase change energy storage building envelope is helpful to effective use of renewable energy, reducing building operational energy consumption, increasing building thermal comfort, and reducing environment pollution and greenhouse gas emission. This paper presents the concept of ideal energy-saving building envelope, which is used to guide the building envelope material selection and thermal performance design. This paper reviews some available researches on phase change building material and phase change energy storage building envelope. At last, this paper presents some current problems needed further research.

The Statistical Theory of Breaking Entrainment Depth and Surface Whitecap Coverage of Real Sea Waves

Abstract Some basic statistics for wave breaking have been derived based on the statistical model of real sea waves. The analytic expressions of breaking entrainment depth and surface whitecap coverage involved with both sea wave characteristics and surface wind velocity have been derived on the basis of the whitecap formation model. The concept of the upper envelope for all the whitecap coverage data versus wind speed has been proposed, and it is assumed to correspond to the whitecap coverage in the case of the infinite wind duration and fetch to determine the model constants. The analytic expressions of breaking entrainment depth and whitecap coverage have been compared with the observations in several ways, and consistently favorable agreement can be found for most observations.

A Nonstandard Generalization of Envelopes

The generalized envelopes are studied by a given nonstandard definition of envelope of a family of lines defined in a projective homogenous coordinates PHC by: u(t)x + v(t) y + w(t) z = 0. The new nonstandard concepts of envelope are applied to conic sections. Our goal in this paper is hat for a given conic section curve f(x,y)=0, we search for the family of lines in which f is its envelope.

Sunscapes: ‘Solar envelopes’ and the analysis of urban DEMs

Abstract The aim of this paper is twofold: first, it simplifies ‘solar envelope’ calculations, making them easier to carry out over extensive urban areas; second, the proposed routines refine the definition of solar envelopes so that they reflect more accurately the actual irradiation of the city and make results directly applicable in urban planning. Both targets can be achieved if we use a new technique for urban analysis, based on the processing of urban digital elevation models (DEMs). The second question, in particular, can be addressed by introducing the concept of ‘iso-solar surfaces’ – surfaces that extend the concept of solar envelope through energy considerations. Our early experiments suggest that iso-solar surfaces may be an effective way to quantify urban irradiation and illumination. As an example, results are presented for the Trade Fair site in Milan, Italy, one of the largest real estate developments currently being implemented in Europe.

Sobolev Spaces with Muckenhoupt Weights, Singularities and Inequalities

Abstract We use the recently introduced concept of growth envelopes to characterize weighted spaces of type , where 𝑤 belongs to some Muckenhoupt 𝐴𝑝 class, and discuss some applications.

USING DOUBLE ENVELOPE METHOD ON A PLANETARY GEAR MECHANISM WITH DOUBLE CIRCULAR-ARC TOOTH

A geometric model and mathematical model of planetary gear mechanism with double circular-arc teeth is determined using the imaginary rack cutters and double envelope concept. The mathematical model of a ring gear with double circular-arc teeth in a second envelope has been developed. In this paper, the conditions of the gear meshing and contact load of the gears are simulated by assembly errors. The goal of the stress analysis is to determine the contact stress on the planet gear and ring gear, and planet gear and sun gear. Given the assembly errors of the planetary gear mechanism including center distance error and mis-aligmment error, the maximum von-Mises stress in the planetary gear mechanism with double circular-arc teeth is analyzed using visualNastran desktop package. It is found that the center distance error is more critical to mis-alignment error.

Nonlinear mode selection in a model of trailing line vortices

Nonlinear mode selection, from initial random Gaussian field perturbations, in a model of trailing line vortices (swirling jets), in the breakdown regime, is addressed by direct numerical simulations with a Reynolds number equal to 1000. A new concept of mode activity in the nonlinear evolution is introduced. The selected modes, according to their activities, are reported and related to strain eigenvectors (with maximum eigenvalues) of the basic flow corresponding to the trailing line vortex under consideration. The selected modes are also related to results from the linear eigenmode (exponential growth) instability theory using the concept of dispersion relation envelope. It is found that the global mode hypothesis of the linear eigenmode theory is violated near the flow axis when the swirl number increases. However, far from the flow axis the linear eigenmode theory is in good agreement with the nonlinear evolution in the breakdown regime. The discrepancy between the nonlinear evolution and the linear eigenmode theory is related to the transient growth of optimal perturbations resulting from the non-normality of the linearized Navier–Stokes equations about shear flows. A clear distinction between an eigenmode, an optimal perturbation (non-modal) and a direct numerical simulation (DNS) mode is made. It is shown that the algebraic (transient) growth contributions from the inviscid continuous spectrum could trigger nonlinearities near the flow axis. The DNS mode selected in the nonlinear regime coincides with the long-wave eigenmode benefiting from the algebraic growth in the linear regime. This eigenmode is different from the short-wave eigenmode with the absolute maximum exponential growth. Although it is promoted by transients, in the linear regime, the long-wave component is selected nonlinearly.

MODELING AND MANUFACTURING OF PP-TYPE SINGLE SCREW COMPRESSOR

A geometric model and a mathematical model of a PP-type single screw rotor with planar gate rotor are derived from the gate-rotor generation process and gear theory. The teeth of gate rotor are planar. Based on the inverse envelope concept, the cutter required for machining the single screw rotor can be obtained using an inverse envelope of a one-parameter family of screw surfaces. The surface of the proposed screw rotor is analyzed using the developed mathematical model. A surface analysis, including stress analysis, of the design and manufacture of the screw compressor is presented. Finally, a numerical example demonstrates the geometric model of the PP-type single screw rotor with a compression ratio of 11:6.

Alternative Funding Plans and Alternative Relationship Plans: Saviours of Academic Medicine or Just the Last Gasp?

The rapid decline of clinician-scientists in all facets of medicine, including gastroenterology, has been well documented. Many groups have also been severely challenged by the inability of their fee-for-service billings to enable them to meet their rapidly expanding educational commitments in addition to sustaining their research programs. Together, these trends have threatened the core academic mission at many Canadian institutions. In the late 1980s, the concept of a provincial government global funding envelope in place of fee-for-service billings was introduced in response to these challenges, and in 1990 the first Alternative Funding Plan (AFP) appeared in the Department of Paediatrics at the Hospital for Sick Children in Toronto, Ontario. We now have four additional AFPs or Alternative Relationship Plans (ARPs) in place, one each at Dalhousie Universtiy (Halifax, Nova Scotia), Queen’s University (Kingston, Ontario), the University of Calgary (Calgary, Alberta) and the University of Alberta (Edmonton, Alberta). Moreover, AFPs are currently being negotiated at all the remaining academic centres in Ontario and are being considered elsewhere in Canada. The existing programs are at various stages of maturity and a number have been renegotiated one or more times with their respective provincial governments and medical associations. In this interview, I have communicated with three heads of gastroenterology (GI) divisions: Dr Ron Bridges (University of Calgary); Dr Des Leddin (Dalhousie University); and Dr William Paterson (Queen’s University). I have also communicated with a previous Chair of Paediatrics, Dr Hugh O’Brodovich (the Hospital for Sick Children), as well as a department head, Dr Jon Meddings (University of Alberta), to gain their insights into whether they believe these funding plans will be the ultimate saviours of academic medicine and what experience and advice they have to offer to those who are considering joining similar programs.

Fatigue Life Supervision of Aircraft Structures under Corrosive Conditions

To consider the corrosive effects on aircraft structural life under natural environments, we have the calendric life to represent its impact. A new concept of Aircraft Structural Life Envelope (ASLE) to consider the combined effects of fatigue loads and corrosive conditions is developed and the sketch of ASLE is presented, then the basic determining methods of ASLE under different corrosive conditions are obtained too. Finally the linear damage cumulative rules are employed to analyze the usage of aircraft in different corrosive conditions, and the residual fatigue life and calendric life of aircraft structures can be predicted and supervised.

Study on an internal gear with asymmetric involute teeth

Abstract In this paper, a double envelope concept is used to determine the basic profile of an internal gear with asymmetric involute teeth including driving and driven gears. The teeth of the proposed gear are asymmetric involute teeth. Based on this concept, a mathematical model of the meshing principles of a driven gear meshed with a driving gear is presented. Here, two gear types are illustrated. One is a spur gear and the other is a helical gear. The double envelope concept is used to determine the driven gear of an internal gear. Based on this concept, the required driving gear can be obtained by the envelope to a one-parameter family of a rack cutter surface. The obtained envelope becomes the generating surface. Then, the driven gear is the envelope for the family of the generating surfaces (driving gear). Through the proposed method, the profile of an internal gear with asymmetric involute teeth can be easily obtained. Using the developed mathematical models and the tooth contact analysis, the kinematic errors are investigated according to the obtained geometric modeling of the designed gear meshing when assembly errors are present. The influence of misalignment on the kinematic errors has been investigated. A comparison of the helical tooth and spur tooth shows that the internal gear with a helical tooth is superior to the internal gear with a spur tooth. Moreover, some results of change of shifting coefficient of internal gear in kinematic errors are studied. The goal of the current study is to investigate von-Mises stress in the proposed internal gear. A structural load is assumed to act on an internal spur gear and an internal helical gear. The rack cutter is shown for design and manufacturing of a driving gear. As an example, the internal gear with a gear ratio of 4:5 was presented. Using rapid prototyping and manufacturing technology, an internal gear with asymmetric involute tooth, a driving gear and a driven gear were manufactured. The rapid prototyping primitives provide an actual full-size physical model that can be analyzed and used for further development. Results from these mathematical models should have applications in the design of internal gear mechanism.