scholarly journals Characterisation of a Mobile Jaw Crusher for Small Scale Mining and Construction Industry

2008 ◽  
Vol 31 (2) ◽  
pp. 113-120
Author(s):  
A.J.M. Itika
Keyword(s):  
Particle Size ◽  
Diesel Engine ◽  
Construction Industry ◽  
Field Test ◽  
Small Scale ◽  
Operating Parameters ◽  
Feed Material ◽  
Jaw Crusher ◽  
Rotary Speed

A small jaw crusher with a crushing capacity of 1 ton per hour has been developed for use in the small scale mining and construction industry. A 3.68 kW air cooled diesel engine was installed to power the crusher. Laboratory and field test were conducted using limestone as feed material at different operating parameters. The analysis of the product from the crusher showed that at a constant jaw gap, coarser products were obtained when the rotary speed was varied from 220 rpm to 300 rpm. With a jaw gap of 25 mm, a higher cumulative undersize fraction was obtained at particle size 25 mm. In contrast, at a jaw gap of 15 mm, highercumulative undersize fraction was obtained at particle size 15 mm. With a feed size 80% passing 60 mm, a finer product was obtained as compared to a feed 80% passing 120 mm. The throughput of the machine increased from 0.4 ton/hr to 0.7 ton/hr when the speed was increased from 220 rpm to 300 rpm. It was found that it is possible to select a combination of operating parameters to achieve a particular goal of operation.

Lessons Learned from Small Scale Field Test Demonstrating CO2 EOR and Geologic Storage at Wellington Field in Southern Kansas

2019 ◽  
Author(s):  
Yevhen Holubnyak ◽  
Willard Watney ◽  
Tiraz Birdie ◽  
Dana Wreath ◽  
George Tsoflias ◽  
...  
Keyword(s):  
Field Test ◽  
Lessons Learned ◽  
Small Scale ◽  
Geologic Storage ◽  
Scale Field ◽  
Co2 Eor

Influence of particle size and operating parameters on virus ultrafiltration efficiency

2011 ◽  
Vol 11 (1) ◽  
pp. 31-38
Author(s):  
Angayar K. Pavanasam ◽  
Ali Abbas ◽  
Vicki Chen
Keyword(s):  
Particle Size ◽  
Filtration Efficiency ◽  
Transmembrane Pressure ◽  
Operating Parameters ◽  
Particle Removal ◽  
Major Step ◽  
Virus Removal ◽  
Virus Particles ◽  
Key Factor ◽  
Effect Of Particle Size

In water treatment, virus removal using ultrafiltration is a major step towards better water quality. In this paper, we study virus filtration efficiency using surrogate virus particles and via statistical surface-response approach. We focus on the effect of particle size (20–100 nm range) as a key factor along with the effects of transmembrane pressure (20–60 kPa range) and feed flowrate (0.3–1.0 L/F;min range) on the filtration virus removal efficiency (LRV). The particle size is shown to impart a great deal of influence on surrogate particle removal. The effect of particle-to-pore-size ratio is reported for comparison of membrane molecular weight cut off (MWCO) performance. It was shown experimentally and through the developed empirical regression model that transmembrane pressure plays a major role in controlling the filtration efficiency along with flowrate. In the studied experimental range, higher LRV values are obtained at lower transmembrane pressure (20 kPa) and at higher feed flowrate (1 L/F;min). Further the effect on LRV of the interaction between transmembrane pressure and particle size seems to be more significant than that of the interaction of flowrate with particle size.

scholarly journals A Social Network-Based Examination on Bid Riggers’ Relationships in the Construction Industry: A Case Study of China

Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 363
Author(s):  
Liang Xiao ◽  
Kunhui Ye ◽  
Junhong Zhou ◽  
Xiaoting Ye ◽  
Ramadhani Said Tekka
Keyword(s):  
Social Network ◽  
Construction Industry ◽  
Small Scale ◽  
High Concentration ◽  
Market Shares ◽  
The Social ◽  
Network Method ◽  
Solid Foundation

Collusive bidding has been an insidious issue in the construction industry. Bidders initiate collusive networks of various sizes to win market shares. The popularity of collusive bidding networks affects market fairness and erodes the interests of market players. Although considerable research efforts were made to diagnose collusive bidding networks, there remains a gap in knowledge regarding the relationships bid riggers use to engage in the networks. Therefore, this study used the social network method, where two hundred sixteen collusion cases were collected from China to test these relationships. The results show that collusive bidding networks were characterized by sparseness, a small scale, a high concentration, and strong randomness. Three types of collusive bidding networks were also detected: contractual, spontaneous, and shadow. Furthermore, these collusive bidding networks had discrepancies regarding participants’ identities, forms of collusive bids, and the determination of bid winners. It was found that the proposed social network model of deliberating bid riggers’ relationships lays a solid foundation for the detection of collusive bidding in the construction sector.

The importance of aerodynamics for prosthetic limb design used by competitive cyclists with an amputation: An introduction

2014 ◽  
Vol 39 (3) ◽  
pp. 232-237 ◽  
Author(s):  
Bryce Dyer
Keyword(s):  
Field Test ◽  
Aerodynamic Drag ◽  
Field Tests ◽  
Field Testing ◽  
Test Method ◽  
Limb Amputation ◽  
Small Scale ◽  
Prosthetic Limb ◽  
Testing Method ◽  
Competitive Cyclists

Background/Objectives: This study introduces the importance of the aerodynamics to prosthetic limb design for athletes with either a lower-limb or upper-limb amputation. Study design: The study comprises two elements: 1) An initial experiment investigating the stability of outdoor velodrome-based field tests, and 2) An experiment evaluating the application of outdoor velodrome aerodynamic field tests to detect small-scale changes in aerodynamic drag respective of prosthetic limb componentry changes. Methods: An outdoor field-testing method is used to detect small and repeatable changes in the aerodynamic drag of an able-bodied cyclist. These changes were made at levels typical of alterations in prosthetic componentry. The field-based test method of assessment is used at a smaller level of resolution than previously reported. Results: With a carefully applied protocol, the field test method proved to be statistically stable. The results of the field test experiments demonstrate a noticeable change in overall athlete performance. Aerodynamic refinement of artificial limbs is worthwhile for athletes looking to maximise their competitive performance. Conclusion: A field-testing method illustrates the importance of the aerodynamic optimisation of prosthetic limb components. The field-testing protocol undertaken in this study gives an accessible and affordable means of doing so by prosthetists and sports engineers. Clinical relevance Using simple and accessible field-testing methods, this exploratory experiment demonstrates how small changes to riders’ equipment, consummate of the scale of a small change in prosthetics componentry, can affect the performance of an athlete. Prosthetists should consider such opportunities for performance enhancement when possible.

Effects of financial management practices on technical performance of building contractors in northeast Nigeria

2020 ◽  
Vol 25 (2) ◽  
pp. 201-223
Author(s):  
Abdulmalik Sa'eed ◽  
Nuru Gambo ◽  
Ibrahim Ibrahim Inuwa ◽  
Innocent Musonda
Keyword(s):  
Developing Countries ◽  
Best Practices ◽  
Construction Industry ◽  
Financial Management ◽  
Management Practices ◽  
Small Scale ◽  
Content Type ◽  
Technical Performance ◽  
Practical Implications ◽  
Northeast Nigeria

Purpose The purpose of this study is to assess the effects of financial management practices of small-scale building contractors on the technical performance of the contractors in the northern part of Nigeria with international best practices. Previous studies argued that the technical performance of small-scale building contractors in developing countries is poor because of insufficient cash to acquire strategic resources at the outset of a project. This continues to pose a challenge to the sustainable development of the construction industry, particularly in developing countries like Nigeria. There is, therefore, a need to identify, assess and compare the effects of financial practices of the contractors with technical performance best practices. Design/methodology/approach The technical performance of each contractor was evaluated using a five-point Likert scale. This is used to obtain the mean technical performance levels of the contractors. A questionnaire survey was administered to the professionals in the industry who were selected by using a proportionate stratified random sampling technique. The contractors’ performance was compared using ANOVA with post hoc, and the effects of contractors’ financial management practices were determined using multiple regression analysis. Findings The results of this study indicated that the contractors in Nigeria were average technical performers and there were large effects of financial management practices on the technical performance of contractors in building projects. Research limitations/implications This study is limited to small-scale building contractors in northeast Nigeria. One of the implications of this study is that it provides the criteria for an evaluation of small-scale building contractors’ technical performance in Nigeria and other developing countries that faced similar problems. Practical implications The practical implications of this study are that it establishes the current level of contractors' technical performance and serves as an awareness of contractors' current financial practices. Social implications This study created bases for self-evaluation of contractors’ technical performance and competition among small-scale contractors in Nigeria for the enhancement of productivity particularly in rural areas for national development. Originality/value This study emanated from the government reports and past studies in the area of performance management based on the persistence of poor technical performance of small-scale contractors in the construction industry.

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