Search results for: bearing capacity ratio

Authors: Rudy Djamaluddin, Arbain Tata, Rita Irmawaty

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The study conducted a simulation of the effect of sea water to the bonding capacity of GFRP sheet on the concrete beams using a simulation tank. As it well known that, fiber reinforced polymer (FRP) has been applied to many purposes for civil engineering structures not only for new structures but also for strengthening of the deteriorated structures. The FRP has advantages such as its corrosion resistance, as well as high tensile strength, to weight ratio. Glass composed FRP (GFRP) sheet is most commonly used due to its relatively lower cost compared to the other FRP materials. GFRP sheet is applied externally by bonding it on the concrete surface. Many studies have been done to investigate the bonding of GFRP sheet. However, it is still very rarely studies on the effect of sea water to the bonding capacity of GFRP sheet on the strengthened beams due to flexural loadings. This is important to be clarified for the wider application of GFRP sheet especially on the flexural structure that directly contact to the sea environment. To achieve the objective of the study, a series of concrete beams strengthened with GFRP sheet on extreme tension surface were prepared. The beams then were stored on the sea water tank for six months. Results indicated the bonding capacity decreased after six months exposed to the sea water.

Keywords: GFRP sheet, sea water, concrete beams, bonding

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Authors: Shaoxi Wang, Pouya Rezai

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High aspect ratio is the necessary parts of complex microstructures. Some methods available to achieve high aspect ratio requires expensive materials or complex process; others is difficult to research simple high aspect ratio structures. The paper presents a simple and cheap two-step Polydimethylsioxane (PDMS) transferring process to get high aspect ratio single pillars, which only requires covering the PDMS mold with Brij@52 surface solution. The experimental results demonstrate the method efficiency and effective.

Keywords: high aspect ratio, microstructure, PDMS, Brij

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Authors: Mohammad Tarek Al Muallim, Ozhan Duzenli, Ceyhun Ilguy

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Passive sonar is a method for detecting acoustic signals in the ocean. It detects the acoustic signals emanating from external sources. With passive sonar, we can determine the bearing of the target only, no information about the range of the target. Target Motion Analysis (TMA) is a process to estimate the position and speed of a target using passive sonar information. Since bearing is the only available information, the TMA technique called Bearing-only TMA. Many TMA techniques have been developed. However, until now, there is not a very effective method that could be used to always track an unknown target and extract its moving trace. In this work, a design of effective Bearing-only TMA Algorithm is done. The measured bearing angles are very noisy. Moreover, for multi-beam sonar, the measurements is quantized due to the sonar beam width. To deal with this, modified gain extended Kalman filter algorithm is used. The algorithm is fine-tuned, and many modules are added to improve the performance. A special validation gate module is used to insure stability of the algorithm. Many indicators of the performance and confidence level measurement are designed and tested. A new method to detect if the target is maneuvering is proposed. Moreover, a reactive optimal observer maneuver based on bearing measurements is proposed, which insure converging to the right solution all of the times. To test the performance of the proposed TMA algorithm a simulation is done with a MATLAB program. The simulator program tries to model a discrete scenario for an observer and a target. The simulator takes into consideration all the practical aspects of the problem such as a smooth transition in the speed, a circular turn of the ship, noisy measurements, and a quantized bearing measurement come for multi-beam sonar. The tests are done for a lot of given test scenarios. For all the tests, full tracking is achieved within 10 minutes with very little error. The range estimation error was less than 5%, speed error less than 5% and heading error less than 2 degree. For the online performance estimator, it is mostly aligned with the real performance. The range estimation confidence level gives a value equal to 90% when the range error less than 10%. The experiments show that the proposed TMA algorithm is very robust and has low estimation error. However, the converging time of the algorithm is needed to be improved.

Keywords: target motion analysis, Kalman filter, passive sonar, bearing-only tracking

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Authors: Zhaojunfeng

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Driven by the national policy of "East Data and Western Calculation", the computing first network will attract a new wave of development. As the foundation of the development of the computing first network, the computing force bearer network has become the key direction of technology research and development in the industry. This article will analyze typical computing force application scenarios and bearing requirements and sort out the SLA indicators of computing force applications. On this basis, this article carries out research and discussion on the key technologies of computing force bearer network in a slice packet network, and finally, gives evolution policy for SPN computing force bearer network to support the development of SPN computing force bearer network technology and network deployment.

Keywords: component-computing force bearing, bearing requirements of computing force application, dual-SLA indicators for computing force applications, SRv6, evolution strategies

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Authors: Arthur Thirion

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Auxetic geometries allow the generation of a negative Poisson ratio (NPR) in conventional materials. This behaviour allows materials to have certain improved mechanical properties, including impact resistance and altered synclastic behaviour. This means these structures have significant potential when it comes to applications as chronic wound dressings. To this end, 6 different "perforated sheet" structure types were 3D printed. These structures all had variations of key geometrical features included cell length and angle. These were tested in compression and tension to assess their Poisson ratio. Both a positive and negative Poisson ratio was generated by the structures depending on the loading. The a/b ratio followed by θ has been shown to impact the Poisson ratio significantly. There is still a significant discrepancy between modelled and observed behaviour.

Keywords: auxetic materials, 3D printing, negative Poisson's ratio, tunable Poisson's ratio

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Authors: Sateesh Kumar Pisini, Swetha Priya Darshini Thammadi, Sanjay Kumar Shukla

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Granular piles are a popular ground improvement technique in soft cohesive soils as well as for loose non-cohesive soils. The present experimental study has been carried out on granular piles in loose (Relative density = 30%) and medium dense (Relative density = 60%) sands with geogrid reinforcement within the sand bed over the granular piles. A group of five piles were installed in the sand at different spacing, s = 2d, 3d and 4d, d being the diameter of the pile. The length (L = 0.4 m) and diameter (d = 50 mm) of the piles were kept constant for all the series of experiments. The load-settlement behavior of reinforced sand bed and granular piles system was studied by applying the load on a square footing. The results show that the effect of reinforcement increases the load bearing capacity of the piles. It is also found that an increase in spacing between piles decreases the settlement for both loose and medium dense soil.

Keywords: granular pile, load-carrying capacity, settlement, geogrid reinforcement, sand

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Authors: Robert L. Burdett, Bayan Bevrani

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Analytical techniques for measuring and planning railway capacity expansion activities have been considered in this article. A preliminary mathematical framework involving track duplication and section sub divisions is proposed for this task. In railways, these features have a great effect on network performance and for this reason they have been considered. Additional motivations have also arisen from the limitations of prior models that have not included them.

Keywords: capacity analysis, capacity expansion, railways, track sub division, track duplication

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Authors: Dalson Figueiredo, Enivaldo Rocha, Ranulfo Paranhos, José Alexandre

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This paper analyzes the effects of institutional capacity on corruption. Methodologically, the research design combines both descriptive and multivariate statistics to examine two original datasets based on secondary data. In particular, we employ a principal component model to estimate an indicator of institutional capacity for both state audit institutions and subnational judiciary courts. Then, we estimate the effect of institutional capacity on two dependent variables: (1) incidence of administrative irregularities and (2) time elapsed to judge corruption cases. The preliminary results using ordinary least squares, negative binomial and Tobit models suggest the same conclusions: higher the institutional audit capacity, higher is the probability of detecting a corruption case. On the other hand, higher the institutional capacity of state judiciary, the lower is the time to judge corruption cases.

Keywords: institutional capacity, corruption, state level institutions, evidence from Brazil

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Authors: Panarat Saengpanya

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There were five objectives in this study including the study of housing type with water environment, the physical and mechanical properties of the buoy material, the mechanical properties of the buoy models, the floating of the buoy models and the relationship between the civil engineering parameters and the floating of the buoy. The buoy examples made from Expanded Polystyrene (EPS) covered by 5 mm thickness of mortar with the equal thickness on each side. Specimens are 0.05 m cubes tested at a displacement rate of 0.005 m/min. The existing test method used to assess the parameters relationship is ASTM C 109 to provide comparative results. The results found that the three type of housing with water environment were Stilt Houses, Boat House, and Floating House. EPS is a lightweight material that has been used in engineering applications since at least the 1950s. Its density is about a hundredth of that of mortar, while the mortar strength was found 72 times of EPS. One of the advantage of composite is that two or more materials could be combined to take advantage of the good characteristics of each of the material. The strength of the buoy influenced by mortar while the floating influenced by EPS. Results showed the buoy example compressed under loading. The Stress-Strain curve showed the high secant modulus before reached the peak value. The failure occurred within 10% strain then the strength reduces while the strain was continuing. It was observed that the failure strength reduced by increasing the total volume of examples. For the buoy examples with same area, an increase of the failure strength is found when the high dimension is increased. The results showed the relationship between five parameters including the floating level, the bearing capacity, the volume, the high dimension and the unit weight. The study found increases in high of buoy lead to corresponding decreases in both modulus and compressive strength. The total volume and the unit weight had relationship with the bearing capacity of the buoy.

Keywords: floating house, buoy, floating structure, EPS

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Authors: Ayse Pekrioglu Balkis, Sawash Mecid

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Due to continued growth and rapid development of road construction in worldwide, road sub-layers consist of soil layers, therefore, identification and recognition of type of soil and soil behavior in different condition help to us to select soil according to specification and engineering characteristic, also if necessary sometimes stabilize the soil and treat undesirable properties of soils by adding materials such as bitumen, lime, cement, etc. If the soil beneath the road is not done according to the standards and construction will need more construction time. In this case, a large part of soil should be removed, transported and sometimes deposited. Then purchased sand and gravel is transported to the site and full depth filled and compacted. Stabilization by cement or other treats gives an opportunity to use the existing soil as a base material instead of removing it and purchasing and transporting better fill materials. Classification of soil according to AASHTOO system and USCS help engineers to anticipate soil behavior and select best treatment method. In this study soil classification and the relation between soil classification and stabilization method is discussed, cement stabilization with different percentages have been selected for soil treatment based on NCHRP. There are different parameters to define the strength of soil. In this study, CBR will be used to define the strength of soil. Cement by percentages, 0%, 3%, 7% and 10% added to soil for evaluation effect of added cement to CBR of treated soil. Implementation of stabilization process by different cement content help engineers to select an economic cement amount for the stabilization process according to project specification and characteristics. Stabilization process in optimum moisture content (OMC) and mixing rate effect on the strength of soil in the laboratory and field construction operation have been performed to see the improvement rate in strength and plasticity. Cement stabilization is quicker than a universal method such as removing and changing field soils. Cement addition increases CBR values of different soil types by the range of 22-69%.

Keywords: California Bearing Ratio, cement stabilization, clayey soil, mechanical properties

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Authors: Alireza Mirzaee, Soosan Abdollahi, Mohammad Abdollahi

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Unreinforced Masonry (URM) wall is vulnerable in resisting horizontal load such as wind and seismic loading. It is due to the low tensile strength of masonry, the mortar connection between the brick units. URM structures are still widely used in the world as an infill wall and commonly constructed with door and window openings. This research aimed to investigate the behavior of URM wall with openings when horizontal load acting on it and developed load-drift relationship of the wall. The finite element (FE) method was chosen to numerically simulate the behavior of URM with openings. In this research, ABAQUS, commercially available FE software with explicit solver was employed. In order to ensure the numerical model can accurately represent the behavior of an URM wall, the model was validated for URM wall without openings using available experimental results. Load-displacement relationship of numerical model is well agreed with experimental results. Evidence shows the same load displacement curve shape obtained from the FE model. After validating the model, parametric study conducted on URM wall with openings to investigate the influence of area of openings and pre-compressive load on the horizontal load capacity of the wall. The result showed that the increasing of area of openings decreases the capacity of the wall in resisting horizontal loading. It is also well observed from the result that capacity of the wall increased with the increasing of pre-compressive load applied on the top of the walls.

Keywords: masonry constructions, performance at earthquake, MSJC-08 (ASD), bearing wall, tie-column

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Authors: Ploychompoo Kittikunchotiwut

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This study examines the relationships between human resource practices, knowledge management capacity, and innovation performance. The data were collected by using a questionnaire from 241 firms in the hotels in Thailand. The hypothesized relationships among variables are examined by using ordinary least square (OLS) regression analysis. The findings show that human resource practices have a positive effect on knowledge management capacity. Besides, knowledge management capacity was found to positively affect innovation performance. Finally, the limitations of the study and directions for future research are discussed.

Keywords: human resource practices, knowledge management capacity, innovation performance

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Authors: Cristina Rodriguez, Abed Alaswad, Zaki El-Hassan, Abdul G. Olabi

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This study investigates the effect on methane production from the waste paper when co-digested with macroalgal biomass as a source of nitrogen. Both feedstocks were previously mechanically pretreated in order to reduce their particle size. Methane potential assays were carried out at laboratory scale in batch mode for 28 days. The study was planned according to two factors: the feedstock to inoculum (F/I) ratio and the waste paper to macroalgae (WP/MA) ratio. The F/I ratios checked were 0.2, 0.3 and 0.4 and the WP/MA ratios were 0:100, 25:75, 50:50, 75:25 and 100:0. The highest methane yield (608 ml/g of volatile solids (VS)) was achieved at an F/I ratio of 0.2 and a WP/MA ratio of 50:50. The methane yield at a ratio WP/MA of 50:50 is higher than for single compound, while for ratios WP/MA of 25:75 and 75:25 the methane yield decreases compared to biomass mono-digestion. This behavior is observed for the three levels of F/I ratio being more noticeable at F/I ratio of 0.3. A synergistic effect was found for the WP/MA ratio of 50:50 and all F/I ratios and for WP/MA=50:50 and F/I=0.2. A maximum increase of methane yield of 49.58% was found for a co-digestion ratio of 50:50 and an F/I ratio of 0.4. It was concluded that methane production from waste paper improves significantly when co-digested with macroalgae biomass. The methane yields from co-digestion were also found higher that from macroalgae mono-digestion.

Keywords: anaerobic co-digestion, biogas, macroalgae, waste paper

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Authors: Yousry El-Sayed Elbolkiny, Mohamed Labib Salem

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Background: Rosemary (ROLE) and costus (SLRE) have been established to show antioxidant effects. Aim: This study aimed to evaluate the ameliorating effects of ROLE and SLRE on the side effects induced by cisplatin (CIS) in tumor-bearing mice. Materials and Methods: Extracts of ROLE and SLRE were examined for their phytochemical activities. To evaluate their anti-tumor effects, mice were inoculated intraperitoneally (i.p.) with 2.5x105 Ehrlich ascites carcinoma (EAC) and then treated i.p. with CIS at days 3-7 and with ROLE (dose) or SLRE (dose) at days 3-14. Mice were sacrificed on day 14 for CBC and T-cell analyses. Results: Phytochemical analysis revealed that both ROLE and SLRE showed similar antioxidant activities. Treatment of EAC-bearing mice with CIS-induced antitumor efficacy of about 90%. Treatment with CIS in combination with ROLE or SLRE did not further enhance the antitumor activity of CIS. However, co-administration of ROLE or SLRE with CIS significantly increased the antitumor efficacy of CIS. Flow cytometric analysis showed that the numbers of CD4+ and CD8+ T cells were decreased in EAC-bearing mice after treatment with CIS. Treatment with both ROLE and SLRE improved the number of these cells. Conclusion: Combinatorial treatment with rosemary and costus can enhance the antitumor activity of CIS

Keywords: CBC, cisplantin, costus, rosemary

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Authors: M. Abdullahi, S. Sadiku, Bashar S. Mohammed, J. I. Aguwa

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The properties of hollow sandcrete blocks produced in Minna, Nigeria are presented. Sandcrete block is made of cement, water and sand bound together in certain mix proportions. For the purpose of this work, fifty (50) commercial sandcrete block industries were visited in Minna, Nigeria to obtain block samples and aggregates used for the manufacture, and to also take inventory of the mix composition and the production process. Sieve analysis tests were conduction on the soil sample from various block industries to ascertain their quality to be used for block making. The mix ratios were also investigated. Five (5) nine inches (9’’ or 225mm) blocks were obtained from each block industry and tested for dimensional compliance and compressive strength. The result of test shows that the grading of the sand falls within the limit required by BS 882: 1990. The sand particles generally satisfy the grading requirement of overall grading and also fall in at least one of the classification of coarse grading, medium grading or fine grading. This clearly indicates that the quality of the aggregates used for the production of sandcrete blocks in Minna, Nigeria are of good quality in terms of grading and workable mix can easily be achieved to obtain high quality product. Physical examinations of the block sizes show slight deviation from the standard requirement in NIS 87:2000. Compressive strength of hollow sandcrete blocks in range of 0.12 N/mm2 to 0.54 N/mm2 was obtained which is below the recommendable value of 3.45 N/mm2 for load bearing hollow sandcrete blocks. This indicates that these blocks are below the standard for load-bearing sandcrete blocks and cannot be used as load bearing walling units. The mix composition also indicated low cement content resulting in low compressive strength. Most of the commercial block industries visited do not take curing very serious. Water were only sprinkled ones or twice before the blocks were stacked and made readily available for sale. It is recommended that a mix ratio of 1:4 to 1:6 should be used for the production of sandcrete blocks and proper curing practice should be adhered to. Blocks should also be cured for 14 days before making them available for consumers.

Keywords: compressive strength, dimensions, mix proportions, sandcrete blocks

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Authors: Zhiqiang Xu, Hongfang Ma, Haitao Zhang, Weixin Qian, Weiyong Ying

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SSZ-13 materials with different Si/Al ratio were prepared by varying the composition of aluminosilicate precursor solutions upon hydrothermal treatment at 150 °C. The Si/Al ratio of the initial system was systematically changed from 12.5 to infinity in order to study the limits of Al composition in precursor solutions for constructing CHA structure. The intermediates and final products were investigated by complementary techniques such as XRD, HRTEM, FESEM, and chemical analysis. NH₃-TPD was used to study the Brønsted acidity of SSZ-13 samples with different Si/Al ratios. The effect of the Si/Al ratio on the precursor species, ultimate crystal size, morphology and yield was investigated. The results revealed that Al species determine the nucleation rate and the number of nuclei, which is tied to the morphology and yield of SSZ-13. The size of SSZ-13 increased and the yield decreased as the Si/Al ratio was improved. Varying Si/Al ratio of the initial system is a facile, commercially viable method of tailoring SSZ-13 crystal size and morphology. Furthermore, SSZ-13 materials with different Si/Al ratio were tested as catalysts for the methanol to olefins (MTO) reaction at 350 °C. SSZ-13 with the Si/Al ratio of 35 shows the best MTO catalytic performance.

Keywords: crystallization, MTO, Si/Al ratio, SSZ-13

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Authors: Kalyani Kulkarni, Bharat Chaudhari

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This paper addresses the issue of resource allocation in the emerging cognitive technology. Focusing the quality of service (QoS) of primary users (PU), a novel method is proposed for the resource allocation of secondary users (SU). In this paper, we propose the unique utility function in the game theoretic model of Cognitive Radio which can be maximized to increase the capacity of the cognitive radio network (CRN) and to minimize the interference scenario. The utility function is formulated to cater the need of PUs by observing Signal to Noise ratio. The existence of Nash equilibrium is for the postulated game is established.

Keywords: cognitive networks, game theory, Nash equilibrium, resource allocation

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Authors: Raymond D. Uzoh, Philip K. Shallsuku, Christopher S. Vaachia

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Selected edible leafy vegetables from North-eastern Nigeria were analysed for their sodium and potassium content in mg/100 g and the ratio Na+/K+ worked out. From experimental results, Venonia amydalina (bitter leaf) contained 150 mg (0.15 g) of sodium and 20500 mg (20.5 g) potassium with a ratio of 0.007, Brassica oleracea var capitata (cabbage) contained 300 mg (0.3 g) of sodium and 19000 mg (19 g) of potassium with a ration of 0.012. Others are Telfairia occidentalis (fluted pumpkin) with 400 mg (0.45 g) of sodium and 19500 mg (19.5 g) of potassium with a ratio of 0.020; Hibiscus sabdriffa (sorrel) has 200 mg (0.2 g) of sodium and 600 mg (0.6 g) of potassium with a ratio of 0.300; and Amarantus caudatus (spinach) contained 450 mg (0.45 g) of sodium and 23000 mg (23 g) of potassium with a ratio of 0.020. The presence of sodium and potassium in foods has become increasingly important as recent studies and dietary information gathered in this research has shown that sodium intake is not the sole consideration in elevated blood pressure but its considered as a ratio Na+/K+ fixed at 0.6. This ratio has been found to be a more important factor, suggesting that our diet should contain 67 % more potassium than sodium.

Keywords: vegetables, sodium, potassium, blood pressure, diet, foods

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Authors: Usha Sivasankaran, Seetha Raman

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Experimental work on Double skin Concrete Filled tubes (DSCFT) are a variation of CFT (Concrete- filled steel tubular) with a hollow core formed by two concentric steel tubes in – filled with concrete. Six Specimens with three different volume fractions of steel fibres are cast and tested. Experiments on circular steel tubes in – filled with steel fibre reinforced concrete (SFRC) and normal concrete have been performed to investigate the contribution of steel fibres to the load bearing capacity of Short Composite Columns. The main Variable considered in the test study is the percentage of steel fibres added to the in –filled concrete. All the specimens were tested under axial compression until failure state realisation. This project presents the percentage Variation in the compression strengths of the 3 types of Composite members taken under Study. The results show that 1.5% SFRC in filled steel columns exhibit enhanced ultimate load carrying capacity.

Keywords: composite columns, optimization of steel, double skin, DSCFT

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Authors: Masoumeh Tadayoni, Saeed Kamyabi, Alireza Entezari

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Background and goal of the research: In planning and management system, the tourism carrying capacity is used as a holistic approach and supportive instrument. Evaluating the carrying capacity is used in quantitative the resource exploitation in line with sustainable development and as a foundation for identifying the changes in natural ecosystem and for the final evaluation and monitoring the tensions and decays in regressed ecosystem. Therefore, the present research tries to determine the carrying capacity of effective, physical and real range of Siahsard tourism region. Method: In the present research, the quantitative analysis of tourism carrying capacity is studied by used of effective or permissible carrying capacity (EPCC), real carrying capacity (PCC) and physical carrying capacity (RCC) in Siahsard fountain. It is analyzed based on the field survey and various resources were used for collecting information. Findings: The results of the analysis shows that, 3700 people use the Siahsard tourism region every day and 1350500 people use it annually. However, the evaluation of carrying capacity can be annually 1390650 people in this place. It can be an important tourism place along with other places in the region. Results: Siahsard’s tourism region has a little way to reach to its carrying capacity that needs to be analyzed. However, based on the results, some suggestions were offered for sustainable development of this region and as the most logical alternations for tourism management.

Keywords: carrying capacity, evaluation, Siahsard, tourism

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Authors: Larry Hawkins, Scott K. Sakakura, Michael J. Salopek

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The Marshall Space Flight Center is designing and building a next-generation CO₂ removal system, the Four Bed Carbon Dioxide Scrubber (4BCO₂), which will use the International Space Station (ISS) as a testbed. The current ISS CO2 removal system has faced many challenges in both performance and reliability. Given that CO2 removal is an integral Environmental Control and Life Support System (ECLSS) subsystem, the 4BCO2 Scrubber has been designed to eliminate the shortfalls identified in the current ISS system. One of the key required upgrades was to improve the performance and reliability of the blower that provides the airflow through the CO₂ sorbent beds. A magnetically levitated blower, capable of higher airflow and pressure than the previous system, was developed to meet this need. The design and qualification testing of this next-generation blower are described here. The new blower features a high-efficiency permanent magnet motor, a five-axis, active magnetic bearing system, and a compact controller containing both a variable speed drive and a magnetic bearing controller. The blower uses a centrifugal impeller to pull air from the inlet port and drive it through an annular space around the motor and magnetic bearing components to the exhaust port. Technical challenges of the blower and controller development include survival of the blower system under launch random vibration loads, operation in microgravity, packaging under strict size and weight requirements, and successful operation during 4BCO₂ operational changeovers. An ANSYS structural dynamic model of the controller was used to predict response to the NASA defined random vibration spectrum and drive minor design changes. The simulation results are compared to measurements from qualification testing the controller on a vibration table. Predicted blower performance is compared to flow loop testing measurements. Dynamic response of the system to valve changeovers is presented and discussed using high bandwidth measurements from dynamic pressure probes, magnetic bearing position sensors, and actuator coil currents. The results presented in the paper show that the blower controller will survive launch vibration levels, the blower flow meets the requirements, and the magnetic bearings have adequate load capacity and control bandwidth to maintain the desired rotor position during the valve changeover transients.

Keywords: blower, carbon dioxide removal, environmental control and life support system, magnetic bearing, permanent magnet motor, validation testing, vibration

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Authors: Marcin Szlachetka, Mateusz Paszko, Grzegorz Baranski

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This paper discusses the AVL EXCITE Designer simulation research into loads applied to main and crank bearings in the compression-ignition two-stroke engine. There was created a model of engine lubrication system which covers the part of this system related to particular nodes of a bearing system, i.e. a connection of main bearings in an engine block with a crankshaft, a connection of crank pins with a connecting rod. The analysis focused on the load given as a distribution of hydrodynamic oil film pressure corresponding different values of radial internal clearance. There was also studied the impact of gas force on minimal oil film thickness in main and crank bearings versus crankshaft rotational speed. Our model calculates oil film parameters, an oil film pressure distribution, an oil temperature change and dimensions of bearings as well as an oil temperature distribution on surfaces of bearing seats. Accordingly, it was possible to select, for example, a correct clearance for each of the node bearings. The research was performed for several values of engine crankshaft speed ranging from 800 RPM to 4000 RPM. Bearing oil pressure was changed according to engine speed ranging between 1 bar and 5 bar and an oil temperature of 90°C. The main bearing clearances made initially for the calculation and research were: 0.015 mm, 0.025 mm, 0.035 mm, 0.05 mm, 0.1 mm. The oil used for the research corresponded the SAE 5W-40 classification. The paper presents the selected research results referring to certain specific operating points and bearing radial internal clearances. Acknowledgement: This work has been realized in the cooperation with The Construction Office of WSK ‘PZL-KALISZ’ S.A. and is part of Grant Agreement No. POIR.01.02.00-00-0002/15 financed by the Polish National Centre for Research and Development.

Keywords: crank bearings, diesel engine, oil film, two-stroke engine

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Authors: N. Perko, N. Kavran, M. Bukljas, I. Berbic

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This paper is a result of implemented research on proposed introduced methodology for nautical ports capacity planning by introducing a multi-criteria approach of defined criteria and impacts at the Adriatic Sea. The purpose was analysing the determinants -characteristics of infrastructure and services of nautical ports capacity allocated, especially nowadays due to COVID-19 pandemic, as crucial for the successful operation of nautical ports. Giving the importance of the defined priorities for short-term and long-term planning is essential not only in terms of the development of nautical tourism but also in terms of developing the maritime system, but unfortunately, this is not always carried out. Evaluation of the use of resources should follow from a detailed analysis of all aspects of resources bearing in mind that nautical tourism used resources in a sustainable manner and generate effects in the tourism and maritime sectors. Consequently, the identified multiplier effect of nautical tourism, which should be defined and quantified in detail, should be one of the major competitive products on the Croatian Adriatic and the Mediterranean. Research of nautical tourism is necessary to quantify the effects and required planning system development. In the future, the greatest threat to the long-term sustainable development of nautical tourism can be its further uncontrolled or unlimited and undirected development, especially under pressure markedly higher demand than supply for new moorings in the Mediterranean. Results of this implemented research are applicable to nautical ports management and decision-makers of maritime transport system development. This paper will present implemented research and obtained result-developed methodology for nautical port capacity planning -port capacity planning multi-criteria decision-making. A proposed methodological approach of multi-criteria capacity planning includes four criteria (spatial - transport, cost - infrastructure, ecological and organizational criteria, and additional services). The importance of the criteria and sub-criteria is evaluated and carried out as the basis for sensitivity analysis of the importance of the criteria and sub-criteria. Based on the analysis of the identified and quantified importance of certain criteria and sub-criteria, as well as sensitivity analysis and analysis of changes of the quantified importance, scientific and applicable results will be presented. These obtained results have practical applicability by management of nautical ports in the planning of increasing capacity and further development and for the adaptation of existing nautical ports. Obtained research is applicable and replicable in other seas, and results are especially important and useful in this COVID-19 pandemic challenging maritime development framework.

Keywords: Adriatic Sea, capacity, infrastructures, maritime system, methodology, nautical ports, nautical tourism, service

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Authors: Angga S. Fajar, Y. Takahashi, J. Kiyono, S. Sawada

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The problem of medium span bridge bearing support in the extreme temperatures fluctuation region is deterioration in case the suppression of superstructure that sustains temperature expansion. The other hand, the behavior and the parameter of RC column accompanied with friction damping mechanism were determined successfully based on the experiment and numerical analysis. This study proposes the structural system of RC pier accompanied with multi sliding friction damping mechanism to substitute the conventional system of pier together with bearing support. In this system, the pier has monolith behavior to the superstructure with flexible small deformation to accommodate thermal expansion of the superstructure. The flexible small deformation behavior is realized by adding the gap mechanism in the multi sliding friction devices form. The important performances of this system are sufficient lateral flexibility in small deformation, sufficient elastic deformation capacity, sufficient lateral force resistance, and sufficient energy dissipation. Numerical analysis performed for this system with fiber element model. It shows that the structural system has good performance not only under small deformation due to thermal expansion of the superstructure but also under seismic load.

Keywords: RC Pier, thermal expansion, multi sliding friction device, flexible small deformation

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Authors: Mario Pérez-Won, Anais Palma-Acevedo, Luis González-Cavieres, Roberto Lemus-Mondaca, Gipsy Tabilo-Munizaga

Abstract:

The Chilean abalone (Concholepas Concholepas) is a gastropod mollusk; it has a high commercial value due to the qualities of its meat, especially hardness, as a critical acceptance parameter. However, its main problem is its short shelf-life which is usually extended using traditional technologies with high energy consumption. Therefore, applying different technologies for the pre-treatment and drying process is necessary. In this research, pulsed electric field (PEF) was used as a pre-treatment for vacuum microwave drying (VMD), freeze-drying (FD), and hot-air drying (HAD). Drying conditions and characteristics were set according to previous experiments. The Drying samples were analyzed in terms of physical quality (color, texture, microstructure, and rehydration capacity), protein quality (degree of hydrolysis and computer protein efficiency ratio), and energy parameters. Regarding quality, the treatment that obtained lower harness was PEF+FD (195 N ± 10), the lowest change of color was for treatment PEF+VMD (ΔE: 17 ± 1.5), and the best rehydration capacity was for treatment PEF+VMD (1.2 h for equilibrium). For protein quality, the highest Computer-Protein Efficiency Ratio was the sample 2.0 kV/ cm of PEF (index of 4.18 ± 0.26 at the end of the digestion). Moreover, about energetic consumption, results show that VMD decreases the drying process by 97% whether PEF was used or not. Consequently, it is possible to conclude that using PEF as a pre-treatment for VMD and FD treatments has advantages that must be used following the consumer’s needs or preferences.

Keywords: chilean abalone, freeze-drying, proteins, pulsed electric fields

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Authors: Marinelle El-Khoury, Lina Bouhaya, Nivine Abbas, Hassan Sleiman

Abstract:

The road network in the north of Lebanon is a prime example of the lack of pavement design and execution in Lebanon.  These roads show major distresses and hence, should be tested and evaluated. The aim of this research is to investigate and determine the deficiencies in road surface design in Lebanon, and to propose an environmentally friendly asphalt mix design. This paper consists of several parts: (i) evaluating pavement performance and structural behavior, (ii) identifying the distresses using visual examination followed by laboratory tests, (iii) deciding the optimal solution where rehabilitation or reconstruction is required and finally, (iv) identifying a sustainable method, which uses recycled material in the proposed mix. The asphalt formula contains Reclaimed Asphalt Pavement (RAP) in the base course layer and in the asphalt layer. Visual inspection of the roads in Tripoli shows that these roads face a high level of distress severity. Consequently, the pavement should be reconstructed rather than simply rehabilitated. Coring was done to determine the pavement layer thickness. The results were compared to the American Association of State Highway and Transportation Officials (AASHTO) design methodology and showed that the existing asphalt thickness is lower than the required asphalt thickness. Prior to the pavement reconstruction, the road materials were tested according to the American Society for Testing and Materials (ASTM) specification to identify whether the materials are suitable. Accordingly, the ASTM tests that were performed on the base course are Sieve analysis, Atterberg limits, modified proctor, Los Angeles, and California Bearing Ratio (CBR) tests. Results show a CBR value higher than 70%. Hence, these aggregates could be used as a base course layer. The asphalt layer was also tested and the results of the Marshall flow and stability tests meet the ASTM specifications. In the last section, an environmentally friendly mix was proposed. An optimal RAP percentage of 30%, which produced a well graded base course and asphalt mix, was determined through a series of trials.

Keywords: asphalt mix, reclaimed asphalt pavement, California bearing ratio, sustainability

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Authors: Xuan Li, Weian Huang, Jinsheng Sun, Fuhao Zhao, Zhiyuan Wang, Jintang Wang

Abstract:

Natural gas hydrates (NGHs) as promising alternative energy sources have gained increasing attention. Hydrate-bearing formation in marine areas is highly unconsolidated formation and is fragile, which is composed of weakly cemented sand-clay and silty sediments. During the drilling process, the invasion of drilling fluid can easily lead to excessive water content in the formation. It will change the soil liquid plastic limit index, which significantly affects the formation quality, leading to wellbore instability due to the metastable character of hydrate-bearing sediments. Therefore, controlling the filtrate loss into the formation in the drilling process has to be highly regarded for protecting the stability of the wellbore. In this study, the temperature-sensitive nanogel of P(NIPAM-co-AMPS-co-tBA) was prepared by soap-free emulsion polymerization, and the temperature-sensitive behavior was employed to achieve self-adaptive plugging in hydrate sediments. First, the effects of additional amounts of AMPS, tBA, and cross-linker MBA on the microgel synthesis process and temperature-sensitive behaviors were investigated. Results showed that, as a reactive emulsifier, AMPS can not only participate in the polymerization reaction but also act as an emulsifier to stabilize micelles and enhance the stability of nanoparticles. The volume phase transition temperature (VPTT) of nanogels gradually decreased with the increase of the contents of hydrophobic monomer tBA. An increase in the content of the cross-linking agent MBA can lead to a rise in the coagulum content and instability of the emulsion. The plugging performance of nanogel was evaluated in a core sample with a pore size distribution range of 100-1000nm. The temperature-sensitive nanogel can effectively improve the microfiltration performance of drilling fluid. Since a combination of a series of nanogels could have a wide particle size distribution at any temperature, around 200nm to 800nm, the self-adaptive plugging capacity of nanogels for the hydrate sediments was revealed. Thermosensitive nanogel is a potential intelligent plugging material for drilling operations in natural gas hydrate-bearing sediments.

Keywords: temperature-sensitive nanogel, NIPAM, self-adaptive plugging performance, drilling operations, hydrate-bearing sediments

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Authors: Tauhidur Rahman, Arnab Kumar Sinha

Abstract:

This paper presents a comparative study of Arch bridges based on their varying rise to span ratio. The comparison is done between different steel Arch bridges which have variable span length and rise to span ratio keeping the same support condition. The aim of our present study is to select the optimum value of rise to span ratio of Arch bridge as the cost of the Arch bridge increases with the increasing of the rise. In order to fulfill the objective, several rise to span ratio have been considered for same span of Arch bridge and various structural parameters such as Bending moment, shear force etc have been calculated for different model. A comparative study has been done for several Arch bridges finally to select the optimum rise to span ratio of the Arch bridges. In the present study, Finite Element model for medium to long span, with different rise to span ratio have been modeled and are analyzed with the help of a Computational Software named MIDAS Civil to evaluate the results such as Bending moments, Shear force, displacements, Stresses, influence line diagrams, critical loads. In the present study, 60 models of Arch bridges for 80 to 120 m span with different rise to span ratio has been thoroughly investigated.

Keywords: arch bridge, analysis, comparative study, rise to span ratio

Procedia PDF Downloads 485

Authors: Bernd Sauer, Michel Werner, Stefan Emrich, Michael Kopnarski, Oliver Koch

Abstract:

Friction reduction is an important aspect in the context of sustainability and energy transition. Rolling bearings are therefore used in many applications in which components move relative to each other. Conventionally lubricated rolling bearings are used in a wide range of applications, but are not suitable under certain conditions. Conventional lubricants such as grease or oil cannot be used at very high or very low temperatures. In addition, these lubricants evaporate at very low ambient pressure, e.g. in a high vacuum environment, making the use of solid lubricated bearings unavoidable. With the use of solid-lubricated bearings, predicting the service life becomes more complex. While the end of the service life of bearings with conventional lubrication is mainly caused by the failure of the bearing components due to material fatigue, solid-lubricated bearings fail at the moment when the lubrication layer is worn and the rolling elements come into direct contact with the raceway during operation. In order to extend the service life of these bearings beyond the service life of the initial coating, the use of transfer lubrication is recommended, in which pockets or sacrificial cages are used in which the balls run and can thus absorb the lubricant, which is then available for lubrication in tribological contact. This contribution presents the results of wear and service life tests on solid-lubricated rolling bearings with sacrificial cage pockets. The cage of the bearing consists of a polyimide (PI) matrix with 15% molybdenum disulfide (MoS2) and serves as a lubrication depot alongside the silver-coated balls. The bearings are tested under high vacuum (pE < 10-2 Pa) at a temperature of 300 °C on a four-bearing test rig. First, investigations of the bearing system within the bearing service life are presented and the torque curve, the wear mass and surface analyses are discussed. With regard to wear, it can be seen that the bearing rings tend to increase in mass over the service life of the bearing, while the balls and the cage tend to lose mass. With regard to the elementary surface properties, the surfaces of the bearing rings and balls are examined in terms of the mass of the elements on them. Furthermore, service life investigations with different material pairings are presented, whereby the focus here is on the service life achieved in addition to the torque curve, wear development and surface analysis. It was shown that MoS2 in the cage leads to a longer service life, while a silver (Ag) coating on the balls has no positive influence on the service life and even appears to reduce it in combination with MoS2.

Keywords: ball bearings, molybdenum disulfide, solid lubricated bearings, solid lubrication mechanisms

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Authors: Ismail Akkaya, Mucip Tapan, Ali Ozvan

Abstract:

Some of the industrially prefabricated buildings located on clayey soils were damaged due to soil conditions. The reasons of these damages are generally due to different settlement capacity, the different plasticity of soils and the level of ground water. The aim of this study is to determine the source of these building damages by conducting in situ tests. Therefore, pressuremeter test, which is one of the borehole loading test conducted to determine the properties of soils under the foundations and Standart Penetration Test (SPT). The results of these two field tests were then used to accurately obtain the consistency and firmness of soils. Pressuremeter Deformation Module (EM) and Net Limiting Pressure (PL) of soils were calculated after the pressuremeter tests. These values were then compared with the SPT (N30) and SPT (N60) results. An empirical equation was developed to obtain EM and PL values of such soils from SPT test results. These values were then used to calculate soil bearing capacity as well as the soil settlement. Finally, the relationship between the foundation settlement and the damage of these buildings were checked. It was found that calculated settlement values were almost the same as measured settlement values.

Keywords: damaged building, pressuremeter, standard penetration test, low and high plasticity clay

Procedia PDF Downloads 293