1,721,010 research outputs found
An Efficient Multi-Core SIMD Implementation for H.264/AVC Encoder
No full textThe optimization process of a H.264/AVC encoder on three different architectures is presented. The architectures are multi- and singlecore and SIMD instruction sets have different vector registers size. The need of code optimization is fundamental when addressing HD resolutions with real-time constraints. The encoder is subdivided in functional modules in order to better understand where the optimization is a key factor and to evaluate in details the performance improvement. Common issues in both partitioning a video encoder into parallel architectures and SIMD optimization are described, and author solutions are presented for all the architectures. Besides showing efficient video encoder implementations, one of the main purposes of this paper is to discuss how the characteristics of different architectures and different set of SIMD instructions can impact on the target application performance. Results about the achieved speedup are provided in order to compare the different implementations and evaluate the more suitable solutions for present and next generation video-coding algorithms
Sustainable design of injection moulded parts by material intensity reduction
No full textLife cycle engineering of injection moulded components is often aimed at minimizing the material intensity mainly by decreasing the part volume and increasing the use of recycled materials, while fulfilling structural and manufacturability requirements. However both these solutions produce an additional environmental impact, due to the higher energy consumption in manufacturing, that is often overlooked. The paper addresses the multi-objective problem of minimizing the overall environmental impact by incorporating the numerical simulation of the process and the structural analysis of the part in a CAD-based shape optimization environment. The proposed approach has been demonstrated through an industrial case study
Development of a test method for the rheological characterization of polymers under the injection molding process conditions
No full textThe reliability of numerical simulations of the injection molding process depends mainly on the rheological characteristics of polymers. The rheological characterization of a polymer for injection molding is commonly carried out by a capillary rheometer. However in this method the measurement is carried out on a sample of unprocessed polymer, neglecting the influence of the plastication phase. This influence is demonstrated in the first part of the paper on a polycarbonate produced by Bayer. To improve the accuracy of rheological data by rejecting these simplifications, a laboratory test method has been developed for the physical simulation of polymers rheology under industrial process conditions. The method is based on an in-line slit-die rheometer which has been mounted as a mould on an injection molding machine. By means of this test it is possible to relate a polymer viscosity not only to its temperature and shear rate but also to those parameters that characterize the plastication process: screw rotation speed, residence time, temperature and geometry of the system
Tool cost estimating at the early stages of Cold forging
Full text linkIdentifying the most appropriate sequence of cold forging operations for a new part requires a number of technological and economical evaluations concerning loads, mechanical properties of the forged component, its producibility on the machines as well as costs for equipment and associate tooling.
This paper presents a methodology for estimating initial and maintenance costs for cold forging tools. This methodology is for use of planners at the early stages of process design, when the sequence of forging operations and equipment are decided and before details of the tooling system are available
Machine timing integrated into an expert CAD/CAE system for cold forging technology
Full text linkCurrent practice in timing and setting-up multi-station forging machines involves
considerable time and effort from skilled manpower. Integrating this activity into a
computerized environme71t for design and engineering of cold forged products ensures
benefits such as des killing of the task and reduction of lead time to manufacture.
The paper describes a computer-aided procedure for timing and setting up of cold
forging multi-station machines, which is a module of an expert CAD/CAE system
integrating all activities in planning the cold forging process. The 'module is based on a
3-D solid representation of the objects moving in the working area and a bne77lJltic
mode! of a· 711171lbcr of diffcrCllt multi-station presses. The user is assisted in idClltifying
suitable timing conditions for the different stages of the tim ing and setting up task.
Capabilities of the module include automatic collision check, collision avoidance
suggestions and integrated CAD-procedure for the design of non-standard grippers
A multiple approach based system for process planning in cold forging: some recent development and applications
Full text linkSome recent developments of a program for sequence planning of rotational cold forged components
are presented. The work is one main task of the BRITE Project "Integrated CAD/CAE System for
Application in Cold Extrusion" and is aimed at the development of an integrated computer-aided
environment for engineering cold forged parts. In this project the authors have collaborated with
process designers of one Italian (Teksid) and three German companies.
In this paper basic CAPP system categories are reviewed. In particular some limits of generative
systems are highlighted to justify the approach presented, based on both automatic and iterative tools.
Consequent upon the approach is the program architecture, which is discussed together with the main
characteristics of the four modules composing the overall program. Afterwards, interactive process
generation is described and functionalities available to generate new geometries are explained. At the
end, some application examples are given
Design of a wear test for hot and warm forging
Full text linkThis paper presents a laboratory simulative test for hot and warm forging tools designed and set-up by
the Authors with the twofold purpose of (i) verifying the applicability of wear micro-mechanical models in
simulation of hot and warm bulk metal forming operations using FEM codes and (ii) evaluating wear
parameters by an inverse numerical technique.
Although its configuration is simple, the test embodies many of the tribosystems encountered in
industrial forging operations and relevant tool wear and failure mechanisms, such as abrasion, thermal
fatigue as well as permanent deformation of tool surface.
The paper focuses on the design of the test configuration and the description of testing and measuring
apparatuses.
The research. work is part of the workprogramme of a European BRITE-EURAM project aimed at
developing a DSS for predicting abrasive and adhesive wear in bulk and sheet forming operations
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