Large-Scale Evaluation of Constrained Bearing Elements Made of Thermosetting Polyester Resin and Polyester Fabric Reinforcement

2006 ◽  
Vol 128 (4) ◽  
pp. 681-696 ◽  
Author(s):  
P. Samyn ◽  
W. Van Paepegem ◽  
J. S. Leendertz ◽  
A. Gerber ◽  
L. Van Schepdael ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Large Scale ◽  
Elastic Recovery ◽  
Small Scale ◽  
Practical Implementation ◽  
Fiber Failure ◽  
Stick Slip ◽  
Composite Surface ◽  
Pull Out ◽  
Stable Sliding

Polymer composites are increasingly used as sliding materials for high-loaded bearings, however, their tribological characteristics are most commonly determined from small-scale laboratory tests. The static strength and dynamic coefficients of friction for polyester/polyester composite elements are presently studied on large-scale test equipment for determination of its bearing capacity and failure mechanisms under overload conditions. Original test samples have a diameter of 250 mm and thickness of 40 mm, corresponding to the practical implementation in the sliding surfaces of a ball-joint, and are tested at various scales for simulation of edge effects and repeatability of test results. Static tests reveal complete elastic recovery after loading to 120 MPa, plastic deformation after loading at 150 MPa and overload at 200 MPa. This makes present composite favorable for use under high loads, compared to, e.g., glass-fibre reinforced materials. Sliding tests indicate stick-slip for pure bulk composites and more stable sliding when PTFE lubricants are added. Dynamic overload occurs above 120 MPa due to an expansion of the nonconstrained top surface. A molybdenum-disulphide coating on the steel counterface is an effective lubricant for lower dynamic friction, as it favorably impregnates the composite sliding surface, while it is not effective at high loads as the coating is removed after sliding and high initial static friction is observed. Also a zinc phosphate thermoplastic coating cannot be applied to the counterface as it adheres strongly to the composite surface with consequently high initial friction and coating wear. Most stable sliding is observed against steel counterfaces, with progressive formation of a lubricating transfer film at higher loads due to exposure of PTFE lubricant. Composite wear mechanisms are mainly governed by thermal degradation of the thermosetting matrix (max. 162°C) with shear and particle detachment by the brittle nature of polyester rather than plastic deformation. The formation of a sliding film protects against fiber failure up to 150 MPa, while overload results in interlaminar shear, debonding, and ductile fiber pull-out.

Mechanisms of Microstructural Rearrangement on Two-Dimensional Aggregates under Compressive Stress

2011 ◽  
Vol 312-315 ◽  
pp. 682-687 ◽  
Author(s):  
Sarunya Promkotra
Keyword(s):  
Large Scale ◽  
Shear Failure ◽  
Elastic Stress ◽  
Tensile Failure ◽  
Small Scale ◽  
Two Dimensional ◽  
Stick Slip ◽  
Elastic And Plastic Deformations ◽  
Elastic Loading ◽  
Air Liquid Interface

Two-dimensional (2D) colloidal aggregates of polystyrene microspheres 4 μm were experimentally modeled to study the rearranged mechanisms and compression behaviors at the air-liquid interface. The aggregated models occurred due to the interaction forces between particles. The combination of mechanical testing technique and the digital video microscopy had been developed to quantitatively analyze the compressive deformation of 2D aggregates. When the compressive forces were applied to the cluster, these forces were transmitted trough the aggregated network during compression. Solid-like mechanical properties of 2D aggregated cluster were examined. Deformation mechanisms occurred within the aggregated network which presented the particle rearrangements during yield. Elastic deformation had undergone the compressive elastic stress of the elastic loading. Rearrangement mechanisms found generally were rolling-hinge, sliding mechanisms and tensile failure for a small-scale deformation. Shear failure and stick-slip mechanisms caused a large-scale plastic deformation. However, across the yield point, the tensile failures were dominated. Rearrangement mechanisms of particles affected both elastic and plastic deformations.

Experimental Validation of a Robust H∞ Control Method on Miniaturized Optical Image Stabilizer Prototypes

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Alireza Alizadegan ◽  
Pan Zhao ◽  
Ryozo Nagamune ◽  
Mu Chiao
Keyword(s):  
Large Scale ◽  
Closed Loop ◽  
Control Method ◽  
Controller Design ◽  
Design Method ◽  
Optical Image ◽  
Small Scale ◽  
Practical Implementation ◽  
Model Parameters ◽  
Experimental Frequency

Abstract This paper validates a robust H∞ controller design method, experimentally, on miniaturized prototypes of the magnetically actuated lens-tilting optical image stabilizers (OISs) with product variabilities. Five small-scale OIS prototypes with product variations are constructed by three-dimensional (3D) printing. For the prototypes, the model parameters are identified based on experimental frequency response data of the prototypes. Using the identified model, a robust H∞ controller is designed to guarantee the robust stability of the closed-loop system and to optimize the closed-loop performance. The experimental results reveal larger and more complex uncertainties in miniaturized OISs with mass-produced parts compared to large-scale prototypes. Despite the increased amount of uncertainties, it is demonstrated that the robust H∞ controller still outperforms the conventional controllers in terms of robust closed-loop stability, performance, and controller order for practical implementation on a mobile phone device.

Les deformations d'age alpin du cristallin du Pelvoux a la lumiere d'observations nouvelles

1952 ◽  
Vol S6-II (4-6) ◽  
pp. 175-190
Author(s):  
Jean Vernet
Keyword(s):  
Plastic Deformation ◽  
Large Scale ◽  
Sedimentary Cover ◽  
Small Scale ◽  
Crystalline Complex

Abstract The discovery of several synclinal zones composed of Carboniferous and Mesozoic strata throws additional light on the structure of the crystalline complex of the Pelvoux massif, France, and substantiates the concept of large-scale plastic deformation with local fracturing on a small scale. The interaction between the crystalline complex and the sedimentary cover during Alpine deformation, both in the massif and in adjacent ranges, is discussed.

scholarly journals Screening of Selected Indicators of Dairy Cattle Welfare in Macedonia

2015 ◽  
Vol 38 (1) ◽  
pp. 43-51 ◽  
Author(s):  
Miroslav Radeski ◽  
Aleksandar Janevski ◽  
Vlatko Ilieski
Keyword(s):  
Dairy Cows ◽  
Large Scale ◽  
Dairy Farms ◽  
Small Scale ◽  
Practical Implementation ◽  
Assessment Protocol ◽  
Key Points ◽  
Full Protocol ◽  
Alarm Threshold ◽  
Welfare Quality

Abstract The welfare state of cattle in dairy farms in Macedonia has never been assessed previously. The objective of this study was to perform screening analysis of dairy cows welfare and to test the practical implementation of the Welfare Quality® Assessment protocol for cattle in dairy farms in Macedonia. In ten small scale and large scale tie stall farms 23 measures were recorded related to 9 welfare criteria of 4 welfare principles (WP) described in the Welfare Quality® Assessment protocol for dairy cows. The mean percentage of very lean cows was 40.5±9.1%. All assessed farms were not providing access to pasture and an outdoor loafing area. Regarding cleanliness, the presence of dirty udder, upper leg/flank and lower leg was 65.2±9.0%, 85.5±8.0% and 86.5±5.8%, respectively. The overall prevalence of lameness was 5.6±5.0%, and for mild and severe alterations it was 30.8±5.8% and 54.1±4.6%, respectively. The ocular and vulvar discharge, diarrhea, dystocia, percentage of downer cows and mortality rate exceeded the warning and alarm threshold. The avoidance - distance test classified 70.4±6.8% as animals that can be touched or approached closer than 50cm, with overall score of 42.9±3.5. This screening reveals that the most welfare concerns are found in the WP Good Feeding and Good Housing. The on-farm welfare assessment using the full protocol on a representative sample of farms in the country is highly recommended for emphasizing the key points for improving the animal welfare in Macedonian dairy farms.

Small-Scale Science to Large-Scale Profession

2000 ◽  
Vol 45 (4) ◽  
pp. 396-398
Author(s):  
Roger Smith
Keyword(s):  
Large Scale ◽  
Small Scale

Development of Physics Learning Module Based on Guided Inquiry with Light Wave Material in Class XI of Senior High School

2020 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Evi Rahmawati ◽  
Irnin Agustina Dwi Astuti ◽  
N Nurhayati
Keyword(s):  
Large Scale ◽  
Learning Strategy ◽  
Student Response ◽  
Average Score ◽  
Small Scale ◽  
Design Development ◽  
Teacher Response ◽  
Student Responses ◽  
Analysis Design ◽  
Scientific Skills

IPA Integrated is a place for students to study themselves and the surrounding environment applied in daily life. Integrated IPA Learning provides a direct experience to students through the use and development of scientific skills and attitudes. The importance of integrated IPA requires to pack learning well, integrated IPA integration with the preparation of modules combined with learning strategy can maximize the learning process in school. In SMP 209 Jakarta, the value of the integrated IPA is obtained from 34 students there are 10 students completed and 24 students are not complete because they get the value below the KKM of 68. This research is a development study with the development model of ADDIE (Analysis, Design, Development, Implementation, and Evaluation). The use of KPS-based integrated IPA modules (Science Process sSkills) on the theme of rainbow phenomenon obtained by media expert validation results with an average score of 84.38%, average material expert 82.18%, average linguist 75.37%. So the average of all aspects obtained by 80.55% is worth using and tested to students. The results of the teacher response obtained 88.69% value with excellent criteria. Student responses on a small scale acquired an average score of 85.19% with highly agreed criteria and on the large-scale student response gained a yield of 86.44% with very agreed criteria. So the module can be concluded receiving a good response by the teacher and students.

Planetary gentrification and urban (re)development

2019 ◽  
Vol 61 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Loretta Lees
Keyword(s):  
Low Income ◽  
Policy Making ◽  
Large Scale ◽  
Urban Redevelopment ◽  
Urban Transformation ◽  
Small Scale ◽  
Income Groups ◽  
Low Income Groups

Abstract Gentrification is no-longer, if it ever was, a small scale process of urban transformation. Gentrification globally is more often practised as large scale urban redevelopment. It is state-led or state-induced. The results are clear – the displacement and disenfranchisement of low income groups in favour of wealthier in-movers. So, why has gentrification come to dominate policy making worldwide and what can be done about it?

AGRICULTURAL PRODUCTION OF CA DONG PEOPLE IN RESETTLEMENT AREA OF TRANH RIVER HYDROPOWER NUMBER 2: CURRENT SITUATION AND IMPACT FACTORS

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Bùi Thị Bích Lan
Keyword(s):  
Social Relations ◽  
Agricultural Production ◽  
Large Scale ◽  
Transition Process ◽  
Impact Factors ◽  
Small Scale ◽  
Scale Production ◽  
Technical Application ◽  
Production Models ◽  
Role Of The State

In Vietnam, the construction of hydropower projects has contributed significantly in the cause of industrialization and modernization of the country. The place where hydropower projects are built is mostly inhabited by ethnic minorities - communities that rely primarily on land, a very important source of livelihood security. In the context of the lack of common productive land in resettlement areas, the orientation for agricultural production is to promote indigenous knowledge combined with increasing scientific and technical application; shifting from small-scale production practices to large-scale commodity production. However, the research results of this article show that many obstacles in the transition process are being posed such as limitations on natural resources, traditional production thinking or the suitability and effectiveness of scientific - technical application models. When agricultural production does not ensure food security, a number of implications for people’s lives are increasingly evident, such as poverty, preserving cultural identity, social relations and resource protection. Since then, it has set the role of the State in researching and building appropriate agricultural production models to exploit local strengths and ensure sustainability.

Managing the impacts of mining on Ghana’s water resources from a legal perspective

2018 ◽  
Vol 1 (3) ◽  
pp. 156-165 ◽  
Author(s):  
Nasirudeen Abdul Fatawu
Keyword(s):  
Surface Water ◽  
Water Resources ◽  
Environmental Protection Agency ◽  
Large Scale ◽  
Small Scale ◽  
Mining Activities ◽  
Protection Agency ◽  
Environmental Laws ◽  
Mining Areas ◽  
Legal Perspective

Recent floods in Ghana are largely blamed on mining activities. Not only are lives lost through these floods, farms andproperties are destroyed as a result. Water resources are diverted, polluted and impounded upon by both large-scale minersand small-scale miners. Although these activities are largely blamed on behavioural attitudes that need to be changed, thereare legal dimensions that should be addressed as well. Coincidentally, a great proportion of the water resources of Ghana arewithin these mining areas thus the continual pollution of these surface water sources is a serious threat to the environmentand the development of the country as a whole. The environmental laws need to be oriented properly with adequate sanctionsto tackle the impacts mining has on water resources. The Environmental Impact Assessment (EIA) procedure needs to bestreamlined and undertaken by the Environmental Protection Agency (EPA) and not the company itself.

RANCANG BANGUN PERANGKAT EKSPERIMENTASI PROSES PIROLISIS BIOMASA GELOMBANG MIKRO

2013 ◽  
Vol 14 (2) ◽  
Author(s):  
Noor Fachrizal
Keyword(s):  
Large Scale ◽  
Continuous Model ◽  
Biomass Energy ◽  
Scale Model ◽  
Small Scale ◽  
Laboratory Apparatus ◽  
Liquid Form ◽  
Large Scale Model ◽  
Bio Oil ◽  
Pyrolysis Of Biomass

Biomass such as agriculture waste and urban waste are enormous potency as energy resources instead of enviromental problem. organic waste can be converted into energy in the form of liquid fuel, solid, and syngas by using of pyrolysis technique. Pyrolysis process can yield higher liquid form when the process can be drifted into fast and flash response. It can be solved by using microwave heating method. This research is started from developing an experimentation laboratory apparatus of microwave-assisted pyrolysis of biomass energy conversion system, and conducting preliminary experiments for gaining the proof that this method can be established for driving the process properly and safely. Modifying commercial oven into laboratory apparatus has been done, it works safely, and initial experiments have been carried out, process yields bio-oil and charcoal shortly, several parameters are achieved. Some further experiments are still needed for more detail parameters. Theresults may be used to design small-scale continuous model of productionsystem, which then can be developed into large-scale model that applicable for comercial use.

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