scholarly journals A Method for Designing Assembly Tolerance Networks of Mechanical Assemblies

2012 ◽  
Vol 2012 ◽  
pp. 1-26 ◽  
Author(s):  
Yi Zhang ◽  
Zongbin Li ◽  
Jianmin Gao ◽  
Jun Hong ◽  
Francesco Villecco ◽  
...  
Keyword(s):  
Geometric Constraints ◽  
Production Costs ◽  
Functional Requirements ◽  
Tree Model ◽  
Assembly Tolerance ◽  
Mechanical Assemblies ◽  
Assembly Structure ◽  
Structure Tree ◽  
Relation Model ◽  
Set Up

When designing mechanical assemblies, assembly tolerance design is an important issue which must be seriously considered by designers. Assembly tolerances reflect functional requirements of assembling, which can be used to control assembling qualities and production costs. This paper proposes a new method for designing assembly tolerance networks of mechanical assemblies. The method establishes the assembly structure tree model of an assembly based on its product structure tree model. On this basis, assembly information model and assembly relation model are set up based on polychromatic sets (PS) theory. According to the two models, the systems of location relation equations and interference relation equations are established. Then, using methods of topologically related surfaces (TTRS) theory and variational geometric constraints (VGC) theory, three VGC reasoning matrices are constructed. According to corresponding relations between VGCs and assembly tolerance types, the reasoning matrices of tolerance types are also established by using contour matrices of PS. Finally, an exemplary product is used to construct its assembly tolerance networks and meanwhile to verify the feasibility and effectiveness of the proposed method.

Variation in oil concentration and economic return from tea-tree (Melaleuca alternifolia Cheel) oil

1990 ◽  
Vol 30 (5) ◽  
pp. 675 ◽  
Author(s):  
GJ Murtagh ◽  
RJ Etherington
Keyword(s):  
Dry Weight ◽  
Production Costs ◽  
Melaleuca Alternifolia ◽  
Tea Tree ◽  
Percentage Points ◽  
Average Production ◽  
Oil Concentration ◽  
The Mean ◽  
Set Up ◽  
Returns On Investment

The oil concentration in tea-tree (Melaleuca alternifolia Cheel) twigs was measured over 8 consecutive days during November 1987, and over 10 out of 12 consecutive days in January 1989. The oil concentration, measured in units of volume of oil per unit dry weight of twigs (v/DW), varied markedly between successive days, from 2.9-1.8% v/DW (a 38% decrease) to 1.8-3.4% v/DW (a 89% increase). The reason for such variation is unknown but it had a pronounced effect on the profitability of growing the crop. The profit, which was expressed as a return on the total set-up cost of $A17 2591ha, was estimated for each of the measured oil concentrations and fixed values of biomass yield, the price of oil and average production costs. The extreme daily variations in oil concentration mentioned above caused the return on investment to decline by 11 percentage points and increase by 16 points, respectively. When measured at the same site, the mean oil concentration increased from 3.1% vPW in November 1987 to 5.8% v/DW in January 1989. As a consequence, the respective mean returns on investment increased from 0 to 26%.

Statistical Tolerance Analysis of Over-Constrained Mechanical Assemblies With Form Defects Considering Contact Types

2019 ◽  
Vol 19 (2) ◽  
Author(s):  
Edoh Goka ◽  
Lazhar Homri ◽  
Pierre Beaurepaire ◽  
Jean-Yves Dantan
Keyword(s):  
Tolerance Analysis ◽  
Optimization Methods ◽  
Optimization Techniques ◽  
Behavior Modeling ◽  
Functional Requirements ◽  
Mechanical Assembly ◽  
Mechanical Assemblies ◽  
Statistical Tolerance ◽  
The Individual ◽  
Statistical Tolerance Analysis

Tolerance analysis aims toward the verification impact of the individual tolerances on the assembly and functional requirements of a mechanism. The manufactured products have several types of contact and are inherent in imperfections, which often causes the failure of the assembly and its functioning. Tolerances are, therefore, allocated to each part of the mechanism in purpose to obtain an optimal quality of the final product. Three main issues are generally defined to realize the tolerance analysis of a mechanical assembly: the geometrical deviations modeling, the geometrical behavior modeling, and the tolerance analysis techniques. In this paper, a method is proposed to realize the tolerance analysis of an over-constrained mechanical assembly with form defects by considering the contacts nature (fixed, sliding, and floating contacts) in its geometrical behavior modeling. Different optimization methods are used to study the different contact types. The overall statistical tolerance analysis of the over-constrained mechanical assembly is carried out by determining the assembly and the functionality probabilities based on optimization techniques combined with a Monte Carlo simulation (MCS). An application to an over-constrained mechanical assembly is given at the end.

Tillage, seeding and fertilizer application technologies

1996 ◽  
Vol 11 (2-3) ◽  
pp. 83-88 ◽  
Author(s):  
Dale E. Wilkins
Keyword(s):  
Water Conservation ◽  
Winter Precipitation ◽  
Soil And Water Conservation ◽  
Plant Diseases ◽  
Production Costs ◽  
Residue Management ◽  
Precipitation Pattern ◽  
Total Production ◽  
Functional Requirements ◽  
Soil And Water

AbstractTillage, seeding and fertilizing implements for rainfed cereal production with a winter precipitation pattern have unique functional requirements. In designing and developing implements for these systems, soil and water conservation principles are critical and must be integrated into the total production system. Plant diseases, insects, weeds, environmental degradation, crop yield, crop quality and economics all may be influenced by tillage, seeding and fe rtilizing implements. Advances have been made in implements f or improved residue management, stand establishment and crop fertilization that leave more crop residue on the surface for soil and water conservation. However, they alter the seed and root zones, often resulting in uncontrolled pests, reduced yields, or increased production costs. Research is needed to integrate production implements into ecosystem management through automatic control systems for improved tillage, se eding and fertilizing. These systems should include field history mapping, real-time soil sens ors, and models to link data bases with equipment functions.

scholarly journals Rainfall parameters affect canopy storage capacity under controlled conditions

2015 ◽  
Vol 75 (4) ◽  
pp. 353-358 ◽  
Author(s):  
Anna Klamerus-Iwan
Keyword(s):  
Sprinkler System ◽  
Influential Factors ◽  
Tree Model ◽  
Precipitation Characteristics ◽  
Simulated Precipitation ◽  
Maximum Water ◽  
The Subject ◽  
Raindrop Size ◽  
Set Up ◽  
Time Required

Abstract The subject of this research was the interception of precipitation, which is defined as the amount of water that can be retained by the entire surface of a tree. The aim was to measure the rate of interception under laboratory conditions in order to determine influential factors. To eliminate water absorption that would occur in living trees, we employed models of deciduous and coniferous trees enabling us to examine the effect of precipitation characteristics and the surface area individually. A sprinkler system that automatically recorded the amounts of water retained on the models was set up in the laboratory. Precipitation was simulated using 5 different intensities with 3 different raindrop sizes. Interception rates were affected by both, the intensity of the precipitation and raindrop size. The time required to reach maximum crown filling with water was variable and depended on plant surface parameters as well as simulated precipitation. The maximum water capacity of crowns was not a constant value even within one tree model, but changed depending on precipitation characteristics

Research of Flight Control System Maintenance Model Based on ARINC624 Specification

2013 ◽  
Vol 760-762 ◽  
pp. 1106-1111
Author(s):  
De Xin Zhou ◽  
Wei Zhang ◽  
Lei Yang
Keyword(s):  
Control System ◽  
Flight Control ◽  
Fault Tree ◽  
Flight Control System ◽  
Tree Model ◽  
Maintenance System ◽  
Structure Tree ◽  
System Maintenance ◽  
Searching Method ◽  
Maintenance Model

According to a detailed study of the fault tree model of the flight control system about Boeing 777, a pre-program was established for the fault tree. The minimal cut sets of the treetops event was calculated by Fussell-Vesely algorithm. And the directed graph search process based on DFS and fault tree module searching method based on double DFLM was used to achieve modular decomposition of fault tree. Therefore, a better structure tree and better rules generate. Finally, it combines the fault tree fault model with the ARINC624 specification to achieve communication requirements between the central maintenance system and flight control system. The Boeing 777 maintenance model was realized.

scholarly journals Innovating Traditional Production Systems Through On-Farm Conservation Agriculture and Agroforestry Research

2022 ◽  
Vol 3 ◽  
Author(s):  
Simon Fonteyne ◽  
Columba Silva Avendaño ◽  
Angel Ramos Sanchez ◽  
Juan Pablo Torres Zambrano ◽  
Fernando García Dávila ◽  
...  
Keyword(s):  
Production Systems ◽  
Smallholder Farmers ◽  
Low Cost ◽  
Conservation Agriculture ◽  
Sustainable Intensification ◽  
Production Costs ◽  
On Farm Conservation ◽  
Input Use ◽  
Traditional Production ◽  
Set Up

Maize (Zea mays L.), the staple crop of Mexico, is often produced by smallholder farmers on sloping terrains. Historically, little agronomic research has been performed under the conditions of these farmers to support them in the sustainable intensification of their production systems. We set up trials at two locations in the state of Oaxaca to evaluate conservation agriculture and agroforestry in collaboration with local farmers. Crop diversification through crop rotations, multicropping, relay cropping or agroforestry increased system yields the most, by up to 1.4 t ha−1 in Teopoxco and 1.7 t ha−1 in Tamazulapam. Increased input use through increased fertilization or liming did not increase profitability enough to justify their use. Zero tillage and residue retention increased yields and reduced production costs. Conservation agriculture with agroforestry was a high-yielding, profitable system that also reduced farmers' risk by providing several harvests per year. The most profitable combinations of agroforestry and conservation agriculture could produce up to $4,854 USD ha−1 in Teopoxco and $2,143 USD ha−1 in Tamazulapam, while the control treatments in the same sites and years produced $175 USD ha−1 and $92 USD ha−1 respectively. In several years the main crop failed, while the trees were able to produce due to their different growing season compared to maize. Through adaptive investigation under farmers' conditions, sustainable intensification of traditional production system is possible with low-cost changes that are locally adapted and within farmers' possibilities.

scholarly journals Gas-Turbine Rotary Regenerator: Design and Development of Prototype Unit for 3000-HP Plant

1956 ◽  
Author(s):  
W. E. Hammond ◽  
T. C. Evans
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Development Program ◽  
Production Costs ◽  
Turbine Plant ◽  
Air Preheater ◽  
Prototype Test ◽  
Set Up ◽  
High Degree ◽  
Gas Turbine Cycle

To exploit the regenerative gas-turbine cycle to the fullest possible extent requires an extremely high degree of heat exchange. Presently, the rotary heat exchanger is the only type which can be designed with the high thermal effectiveness necessary and yet remain practical from a size and cost standpoint. The mechanical nature of the rotary heat exchanger is such, however, that some leakage of high-pressure fluid to the low-pressure side will always occur. The fact that in the past this leakage could not be held to workable values has prevented commercial acceptance of this type unit. Consequently, The Air Preheater Corporation set up an intensive program aimed at developing an acceptable sealing means which would remove this one objection to an otherwise highly desirable piece of equipment. While this development program, at time of writing, is far from complete, results to-date have indicated that sealing of the rotary design can be accomplished, and based on quantity production, costs of a turbine plant equipped with a rotary heat exchanger would be attractive commercially. Included in the development program was the design and construction of a prototype unit for a 3000 hp turbine plant. While erection of the prototype unit is complete, no testing has been done at time of writing. The purpose of this paper is to emphasize the advantages of the regenerative cycle, generally, and more specifically, to show why the rotary type is most promising, particularly in the high effectiveness range. In addition, certain data pertaining to the design of the prototype unit are also presented. A future report will present results obtained from the prototype test program.

Design and Evaluation of a New-Type Multifunctional Machine Tool - Functional Requirements and Design -

1997 ◽  
Vol 9 (6) ◽  
pp. 427-433 ◽  
Author(s):  
Nobuhiro Sugimura ◽  
◽  
Shigeru Ueno ◽  
Nozomi Mishima ◽  
Soichi Hachiga ◽  
...  
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Scale Model ◽  
Manufacturing Processes ◽  
Functional Requirements ◽  
Machining Processes ◽  
Mechanical Products ◽  
New Type ◽  
Set Up ◽  
Basic Configuration

The objective of this research is to develop a new type of flexible and multifunctional machine tool which can be integrated into such manufacturing processes as machining, inspection and the heat treatment of mechanical products. The functional requirements of the multifunctional machine tools were initially analyzed based on a questionnaire given to both the users and the designers of machine tools. The basic configuration of the machine tool is proposed to conform to the functional requirements. The configuration designed has two main spindles, for both the tool and the work, one subspindle, and eight rotational and linear feed axes. All the machining processes of turning, milling, 5-axis machining of sculpted surfaces, grinding, slotting gear shaving and laser processing can be carried out using the proposed machine tool without the need for manual set-ups. A simulation model and a scale model are developed that simulate the manufacturing motion processes and the set-up processes of the machine tool.

Sign in / Sign up

Export Citation Format

Share Document