Search results for: resistance to compression

Authors: Xiaohui Wang, Liwei Sun, Guilin Zhang

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Printed circuit board (PCB) is the carrier of electronic components. Its coating is the first barrier for protecting itself. If the coating is damaged, the performance of printed circuit board will decrease rapidly until failure. Therefore, the coating plays an important role in the entire printed circuit board. There are common four kinds of coating of printed circuit board that the material of the coatings are paryleneC, acrylic, polyurethane, silicone. In this paper, we designed an accelerated degradation test of humid and heat for these four kinds of coating. And chose insulation resistance, moisture absorption and surface morphology as its test indexes. By comparing the change of insulation resistance of the coating before and after the test, we estimate failure time of these coatings based on the degradation of insulation resistance. Based on the above, we estimate the service life of the four kinds of PCB.

Keywords: printed circuit board, life assessment, insulation resistance, coating material

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Authors: Ihn Sook Jeong, Eun Joo Lee, Jae Hyung Kim, Gun Ho Kim, Young Jun Hwang

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This study investigated intravenous (IV) infiltration using bioelectrical impedance for 27 hospitalized patients in a long-term care hospital. Impedance parameters showed significant differences before and after infiltration as follows. First, the resistance (R) after infiltration significantly decreased compared to the initial resistance. This indicates that the IV solution flowing from the vein due to infiltration accumulates in the extracellular fluid (ECF). Second, the relative resistance at 50 kHz was 0.94 ± 0.07 in 9 subjects without infiltration and was 0.75 ± 0.12 in 18 subjects with infiltration. Third, the magnitude of the reactance (Xc) decreased after infiltration. This is because IV solution and blood components released from the vein tend to aggregate in the cell membrane (and acts analogously to the linear/parallel circuit), thereby increasing the capacitance (Cm) of the cell membrane and reducing the magnitude of reactance. Finally, the data points plotted in the R-Xc graph were distributed on the upper right before infiltration but on the lower left after infiltration. This indicates that the infiltration caused accumulation of fluid or blood components in the epidermal and subcutaneous tissues, resulting in reduced resistance and reactance, thereby lowering integrity of the cell membrane. Our findings suggest that bioelectrical impedance is an effective method for detection of infiltration in a noninvasive and quantitative manner.

Keywords: intravenous infiltration, impedance, parameters, resistance, reactance

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Authors: Muhammad Sheeraz

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Literary responses to various forms of local and international oppressions can be found in all major Pakistani languages and their academic study is crucial to understand the local creative and critical mind. However, most of them have not yet received as much of scholarly attention as has the Anglophone Pakistani literature of this kind. One of the reasons for this indifference is that resistance literature is usually mistaken as incidental work produced in haste and thus not a serious subject or high art worthy of being considered critically. Literary criticism in the English language did not include this Urdu resistance literature because most of it has not yet been translated into English, and scholars proficient in Urdu and producing critical works in English have contented themselves to the critique of a few prominent writers of Urdu, for instance, Faiz Ahmad Faiz and Saadat Hassan Manto. While there is no denying the fact that they hold a significant position in Pakistani literature, the tradition of resistance is in no way limited to them. Bringing to the limelight other resistant voices from Urdu fiction, this qualitative research employs Barbara Harlow’s framework of postcolonial resistance literature to explore the strategy of silencing as used in twenty three short stories written between the military regime of Zia ul Haq (1977-1988) in Pakistan. The study shows that the writers of these Urdu short stories have not only recorded various tools of silencing employed by the oppressors but also represented various kinds of silences that were observed in the society. Moreover, they have also depicted how this silencing was dealt with by the writers and intellectual of the time. Thus, in the light of the analysis, it can be safely said that Urdu resistance literature notices, recounts, and theorizes silencing and silences within the local sociopolitical condition.

Keywords: resistance literature, Urdu short fiction, Zia ul Haq, postcolonialism

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Authors: Nadia Hammouda, K. Belmokre

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Organic coatings are widely employed in the corrosion protection of most metal surfaces, particularly steel. They provide a barrier against corrosive species present in the environment, due to their high resistance to oxygen, water and ions transport. This study focuses on the evaluation of corrosion protection performance of epoxy paint on the carbon steel surface in sea water by Electrochemical Impedance Spectroscopy (EIS). The electrochemical behavior of painted surface was estimated by EIS parameters that contained paint film resistance, paint film capacitance and double layer capacitance. On the basis of calculation using EIS spectrums it was observed that pore resistance (Rpore) decreased with the appearance of doubled layer capacitance (Cdl) due to the electrolyte penetration through the film. This was further confirmed by the decrease of diffusion resistance (Rd) which was also the indicator of the deterioration of paint film protectiveness.

Keywords: epoxy paints, carbon steel, electrochemical impedance spectroscopy, corrosion mechanisms, sea water

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Authors: Eliott Guérin, Remi Daudin, Georges Kalepsi, Alexis Lenain, Sebastien Gravier, Benoit Ter-Ovanessian, Damien Fabregue, Jean-Jacques Blandin

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Due to interesting compromise between mechanical and corrosion properties, Zr-based BMGs are attractive for biomedical applications. However, the enhancement of their glass forming ability (GFA) is often achieved by addition of toxic elements like Ni or Be, which is of course a problem for such applications. Consequently, the development of Ni-free Be-free Zr-based BMGs is of great interest. We have developed a Zr-based (Ni and Be-free) amorphous metallic alloy with an elastic limit twice the one of Ti-6Al-4V. The Zr56Co28Al16 composition exhibits a yield strength close to 2 GPa and low Young’s modulus (close to 90 GPa) [1-2]. In this work, we investigated Niobium (Nb) addition through substitution of Zr up to 8 at%. Cobalt substitution has already been reported [3], but we chose Zr substitution to preserve the glass forming ability. In this case, we show that the glass forming ability for 5 mm diameters rods is maintained up to 3 at% of Nb substitution using suction casting in cooper moulds. Concerning the thermal stability, we measure a strong compositional dependence on the glass transition (Tg). Using DSC analysis (heating rate 20 K/min), we show that the Tg rises from 752 K for 0 at% of Nb to 759 K for 3 at% of Nb. Yet, the thermal range between Tg and the crystallisation temperature (Tx) remains almost unchanged from 33 K to 35 K. Uniaxial compression tests on 2 mm diameter pillars and 3 points bending (3PB) tests on 1 mm thick plates are performed to study the Nb addition on the mechanical properties and the plastic behaviour. With these tests, an optimal Nb concentration is found, improving both plasticity and fatigue resistance. Through interpretations of DSC measurements, an attempt is made to correlate the modifications of the mechanical properties with the structural changes. The optimized chemical, structural and mechanical properties through Nb addition are encouraging to develop the potential of this BMG alloy for biomedical applications. For this purpose, we performed polarisation, immersion and cytotoxicity tests. The figure illustrates the polarisation response of Zr56Co28Al16, Zr54Co28Al16Nb2 and TA6V as a reference after 2h of open circuit potential. The results show that the substitution of Zr by a small amount of Nb significantly improves the corrosion resistance of the alloy.

Keywords: metallic glasses, amorphous metal, medical, mechanical resistance, biocompatibility

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Authors: Fanyuan Shao, Wei Liu, Deli Gao

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Polycrystalline diamond composite (PDC) cutter is made of diamond powder as raw material, cobalt metal or non-metallic elements as a binder, mixed with WC cemented carbide matrix assembly, through high temperature and high-pressure sintering. PDC bits with PDC cutters are widely used in oil and gas drilling because of their high hardness, good wear resistance and excellent impact toughness. And PDC cutter is the main cutting tool of bit, which seriously affects the service of the PDC bit. The wear resistance of the PDC cutter is measured by cutting granite with a vertical turret lathe (VTL). This experiment can achieve long-distance cutting to obtain the relationship between the wear resistance of the PDC cutter and cutting distance, which is more closely to the real drilling situation. Load cell and 3D optical profiler were used to obtain the value of cutting forces and wear area, respectively, which can also characterize the damage and wear of the PDC cutter. PDC cutters were cut via electrical discharge machining (EDM) and then flattened and polished. A scanning electron microscope (SEM) was used to observe the distribution of binder cobalt and the size of diamond particles in a diamond PDC cutter. The cutting experimental results show that the wear area of the PDC cutter has a good linear relationship with the cutting distance. Simultaneously, the larger the wear area is and the greater the cutting forces are required to maintain the same cutting state. The size and distribution of diamond particles in the polycrystalline diamond layer have a great influence on the wear resistance of the diamond layer. And PDC cutter with fine diamond grains shows more wear resistance than that with coarse grains. The deep leaching process is helpful to reduce the effect of binder cobalt on the wear resistance of the polycrystalline diamond layer. The experimental study can provide an important basis for the application of PDC cutters in oil and gas drilling.

Keywords: polycrystalline diamond compact, scanning electron microscope, wear resistance, cutting distance

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Authors: Jayakrishnan U.

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A concept of adding two strokes to a four stroke Otto or Diesel engine cycle presented here for the waste heat recovery in a four stroke internal combustion engine. Four stroke Diesel cycle and Otto cycle engines have very low thermal efficiency due to high amount of energy loss in exhaust and also on the cooling of the engine. It is estimated about 35 percent of fuel energy is lost in exhaust of engine and 30 percent in cooling of engine. So by modifying a four-stroke Otto or Diesel engine by adding two-stroke heat recovery steam cycle is presented here. Water injection is used to get an additional power stroke by partial compression of the exhaust gases at the end of third stroke in a four stroke I.C.Engine. It is the conversion of a four-stroke cycle to a six-stroke cycle. By taking a four stroke petrol engine of known dimensions, an ideal thermodynamic model is used to analyse and calculate the events of exhaust gas compression and following two strokes of water injection. By changing the exhaust valve closing timing during exhaust stroke and analysing it on various points, an optimum amount of exhaust gas re-compression and amount of water injection can be found for maximizing efficiency and fuel economy. It is achieved by changing the exhaust valve timing and finding an optimum amount of exhaust re-compression, maximizing the net mean effective pressure of the steam expansion stroke (MEPsteam). Specific fuel consumption of the engine also decreases increasing the fuel economy. The valve closing timings for maximum MEPsteam is limited by either 1 bar or dew point temperature of expansion gas or moisture mixture to avoid moisture formation. By modifying the four-stroke Otto or Diesel cycle by adding two water injection stroke has the potential to significantly increase the engine efficiency and fuel economy.

Keywords: internal combustion engine, engine efficiency, six-stroke cycle, water injection, specific fuel consumption

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Authors: Mintesinot Teshome Mengsha

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Reinforced concrete structural walls are provided in structures to decrease horizontal displacements under seismic loads. The cyclic lateral load resistance capacity of a structural wall is controlled by two parameters, the strength and the ductility; it is better to have the shear strength somewhat greater than the compression to prevent shear failure, which is brittle, sudden and of serious consequence. Due to architectural and functional reasons, small openings are provided in this important structural part. The main objective of this study is to investigate the finite element of RC structural walls with small openings subjected to cyclic load using the finite element approach. The experimental results in terms of load capacity, failure mode, crack pattern, flexural strength, shear strength, and deformation capacity.

Keywords: ABAQUS, finite element method, small openings, reinforced concrete structural walls

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Authors: Viriyavudh Sim, Woo Young Jung

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Performance of Basalt Fiber Reinforced Polymer (BFRP) sandwich infill panel system under diagonal compression was studied by means of numerical analysis. Furthermore, the variation of temperature was considered to affect the mechanical properties of BFRP, since their composition was based on polymeric material. Moreover, commercial finite element analysis platform ABAQUS was used to model and analyze this infill panel system. Consequently, results of the analyses show that the overall performance of BFRP panel had a 15% increase compared to that of GFRP infill panel system. However, the variation of buckling load in terms of temperature for the BFRP system showed a more sensitive nature compared to those of GFRP system.

Keywords: basalt fiber reinforced polymer (BFRP), buckling performance, numerical simulation, temperature dependent materials

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Authors: Pei-Jung Wu, Ching-Ying Huang, Chih-Chia Lin, Chun-Han Li, Chien-Yuan Wang

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The fuel cell market has considerable development potential, but the cost is still less competitive. Replacing the traditional graphite plate with a stainless steel plate as a bipolar plate can greatly reduce the weight and volume of the stack, and has more cost advantages. However, the passivation layer on the surface of stainless steel makes the contact resistance reach the ohmic level and reduces the performance of the fuel cell. Therefore, it is necessary to reduce the interfacial contact resistance through the surface treatment. In this research, the thickness, uniformity, interfacial contact resistance (ICR), and adhesion of the carbon-based layer was analyzed. On the other hand, the effect of coating properties on the performance of the fuel cell was verified through I-V tests. The results show that after coating the contact resistance is greatly reduced by three stages to the microohm level, and as the film thickness is reduced, the contact resistance is reduced from 229~118 mΩ-cm² to 135~73 mΩ-cm² at a general assembly pressure of 1 to 2 MPa., and the current density at 0.6 V increased from 485.7 mA/cm² to 575.7 mA/cm². This study verifies the importance of the uniformity and ICR of the coating on proton exchange membrane fuel cell (PEMFC), and the surface coating technology is the key to affecting the characteristics of the coating.

Keywords: contact resistance, proton exchange membrane fuel cell, PEMFC, SS bipolar plate, spray coating process

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Authors: Naomi Seidu, Edward Poluyi, Chibuikem Ikwuegbuenyi, Eghosa Morgan

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The current poor prognosis of glioblastoma has called for the need for an improvement in treatment methods in order to improve its survival rate. Despite the different interventions currently available for this tumor, the average survival is still only a few months. (12-15). The aim is to create a more favorable prognosis and have a reduction in the resistance to treatment currently being experienced, even with surgical interventions and chemotherapy. From the available literature, there is a relationship between the presence of HOX genes (Homeobox genes) and glioblastoma, which could be attributable to the increasing treatment resistance. Hence silencing these genes can be a key to improving survival rates of glioblastoma. A series of studies have highlighted the role that HOX genes play in glioblastoma prognosis. Promotion of human glioblastoma initiation, aggressiveness, and resistance to Temozolomide has been associated with HOXA9. The role of HOX gene expression in cancer stem cells should be studied as it could provide a means of designing CSC-targeted therapies, as CSCs play a part in the initiation and progression of solid tumors.

Keywords: GBM- glioblastoma, HOXA gene- homeobox genes cluster, signaling pathways, temozolomide

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Authors: Wilhelm Hoeflinger, Thomas Laminger, Johannes Wolfslehner

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For vacuum cleaned dust filters, used e. g. in textile industry, there exist no calculation methods to determine design parameters (e. g. traverse speed of the nozzle, filter area...). In this work a method to calculate the optimum traverse speed of the nozzle of an industrial-size flat dust filter at a given mean pressure drop and filter face velocity was elaborated. Well-known equations for the design of a cleanable multi-chamber bag-house-filter were modified in order to take into account a continuously regeneration of a dust filter by a nozzle. Thereby, the specific filter medium resistance and the specific cake resistance values are needed which can be derived from filter tests under constant operation conditions. A lab-scale filter test rig was used to derive the specific filter media resistance value and the specific cake resistance value for vacuum cleaned filter operation. Three different filter media were tested and the determined parameters were compared to each other.

Keywords: design of dust filter, dust removing, filter regeneration, operation parameters

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Authors: Nadia Hammouda, Kamel Belmokre

Abstract:

Organic coatings are widely employed in the corrosion protection of most metal surfaces, particularly steel. They provide a barrier against corrosive species present in the environment, due to their high resistance to oxygen, water and ions transport. This study focuses on the evaluation of corrosion protection performance of epoxy paint on the carbon steel surface in sea water by Electrochemical Impedance Spectroscopy (EIS). The electrochemical behavior of painted surface was estimated by EIS parameters that contained paint film resistance, paint film capacitance and double layer capacitance. On the basis of calculation using EIS spectrums it was observed that pore resistance (Rpore) decreased with the appearance of doubled layer capacitance (Cdl) due to the electrolyte penetration through the film. This was further confirmed by the decrease of diffusion resistance (Rd) which was also the indicator of the deterioration of paint film protectiveness.

Keywords: epoxy paints, carbon steel, electrochemical impedance spectroscopy, corrosion mechanisms, sea water

Procedia PDF Downloads 353

Authors: Liaqat Ali, Khalid Farooq, Shafieullah Khan, Nasir Orakzai, Qudratullah

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Objectives: To determine the risk factors for high resistance of ciprofloxacin in complicated urinary tract infections. Materials and Methods: It is an analytical study that was conducted in the department of Urology (Team ‘C’) at Institute of Kidney Diseases Hayatabad Peshawar from 1st June 2012 till 31st December 2012. Total numbers of 100 patients with complicated UTI was selected in the study. Multivariate analysis and linear regression were performed for the detection of risk factors. All the data was recorded on structured Proforma and was analyzed on SPSS version 17. Results: The mean age of the patient was 55.6 years (Range 3-82 years). 62 patients were male while 38 patients were female. 66 isolates of E-Coli were found sensitive to ciprofloxacin while 34 isolates were found Resistant for ciprofloxacin. Using multivariate analysis and linear regression, an increasing age above 50 (p=0.002) History of urinary catheterization especially for bladder outflow obstruction (p=0.001) and previous multiple use of ciprofloxacin (p=0.001) and poor brand of ciprofloxacin were found to be independent risk factors for high resistance of ciprofloxacin. Conclusion: UTI is common illness across the globe with increasing trend of antimicrobial resistance for ciprofloxacin against E Coli in complicated UTI. The risk factors for emerging resistance are increasing age, urinary catheterization and multiple use and poor brand of ciprofloxacin.

Keywords: urinary tract infection, ciprofloxacin, urethral catheterization, antimicrobial resistance

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Authors: Liqiang Gong, Hanguang Fu

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In order to further improve the wear resistance of Hypereutectic High Chromium Cast iron (HHCCI), the effects of different Cu contents on the microstructure and properties of HHCCI were systematically studied. It was found that with the increase of Cu content, the carbide size was refined, and the increase of Cu content led to the increase of austenite and the decrease of hardness in as-cast HHCCI. After heat treatment at 1050 °C, the hardness of HHCCI increased significantly compared with as-cast. And with the increase of Cu content, the hardness of HHCCI increased first and then decreased, and the hardness was the highest when 0.5 wt.% Cu was added. The increase of copper content promotes the precipitation of secondary carbides and makes the interface between α-Fe and M23C6-type secondary carbides a semi-coherent boundary. With the increase of Cu content, the wear loss of HHCCI decreased after heat treatment at 1050 °C, and the wear resistance improved. When the Cu content increased to 1.0 wt.%, the wear resistance of HHCCI was the best, which was 2.6 times that of copper-free HHCCI. The continued increase of copper content has no obvious effect on the wear resistance of HHCCI. In addition, a small amount of Cu tends to adsorb on the (0001) preferential growth surface of M₇C₃-type carbides, thereby refining the carbides. From the First-principles calculations, the solid solution strengthening effect of Cu on the matrix and the adsorption and refinement of carbides were revealed, and the influence mechanism on the wear resistance of HHCCI was characterized.

Keywords: hypereutectic high chromium cast iron, cu alloying, carbides, wear resistance, first-principles calculations

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Authors: Shelin Jin, Jin Huang, Shiqin Cao, Qiuzhen Jia, Bo Zhang, Zhenyu Sun

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Stripe rust and leaf rust, caused by Puccinia striiformis f.sp. tritici and Puccinia recondita f.sp. tritici are two of the most damaging diseases of wheat in China. In recent years, leaf rust has migrated to some wheat growing areas previously suitable for stripe rust, resulting in a mixture of the two diseases occurring in the same area and at the same time, and seriously damage wheat production in China, Gansu Province. The most effective method of prevention those two diseases are through the use of resistant cultivars. However, many studies have only carried out of resistance of wheat varieties for a single disease; resistance to both diseases is unknown. In order to definite the resistance composition of wheat varieties to these two diseases, 715 wheat varieties/lines from 8 breeding units in Gansu province were collected to test for the resistance to stripe rust and leaf rust at seedling stage in greenhouse and at adult plant stage in field in 2016-2018, respectively. Spore suspensions with the fresh mixture races of CYR32, CYR33, and CYR34 of Puccinia striiformis f.sp. tritici and mixture races of THTP, THTT, TKTT, and THTS of Puccinia recondita f.sp. tritici were used for inoculation separately. The result shows that only 4.74% of the varieties/lines show comprehensive resistance to strip rust and leaf rust at all growth stages, and there are 34 wheat varieties/lines including Tianxuan 67, 2006-1-4-1-4-2-7-2-3-10, 03-139-1-2-2-1-2-1, Qingnong 21, Lenghan 5, 04-203-1-1-1 and so on. In seedling stage, the frequencies of resistant varieties/lines to wheat strip rust and leaf rust were 56.64% and 30.23%. While the materials were susceptible to these diseases were 43.36% and 69.77%. 71 varieties/lines were resistant to those two diseases, accounted for 9.93%. 10 varieties/lines, accounted for 1.4%, were highly resistant (including immune/near immune) to those two diseases. In adult-plant stage, the frequencies of resistant varieties/lines to wheat strip rust and leaf rust were 76.53% and 36.11%. While the materials were susceptible to these diseases were 23.47% and 63.89%. 137 varieties/lines were resistant to those two diseases, accounted for 19.16%. 59 varieties/lines, accounted for 8.25%, were highly resistant (including immune/near immune) to those two diseases. Overall, the 715 varieties /lines had high resistance to wheat strip rust, but poor resistance to leaf rust. This study found out some resistant materials which had better comprehensive resistance to leaf rust and strip rust, also pointed out the resistance characteristics of 715 varieties/lines to those two diseases at the seedling stage and adult-plant stage, which will be of great guiding significance in wheat resistance breeding and comprehensive control those two diseases in China, Gansu Province in the future.

Keywords: Puccinia striiformis f.sp. tritici, Puccinia recondita f.sp. tritici, resistance of variety, wheat

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Authors: Preeti Kumari, Ridhi Kapoor

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 In any communication, security is the most important issue in today’s world. In this paper, steganography is the process of hiding the important data into other data, such as text, audio, video, and image. The interest in this topic is to provide availability, confidentiality, integrity, and authenticity of data. The steganographic technique that embeds hides content with unremarkable cover media so as not to provoke eavesdropper’s suspicion or third party and hackers. In which many applications of compression, encryption, decryption, and embedding methods are used for digital image steganography. Due to compression, the nose produces in the image. To sustain noise in the image, the LSB insertion technique is used. The performance of the proposed embedding system with respect to providing security to secret message and robustness is discussed. We also demonstrate the maximum steganography capacity and visual distortion.

Keywords: steganography, LSB, encoding, information hiding, color image

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Authors: Ayman K. El Essawy, Amal M. Hosny, Hala M. Abu Shady

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The rapid detection of TB and drug resistance, both optimizes treatment and improves outcomes. In the current study, respiratory specimens were collected from 155 patients. Conventional susceptibility testing and MIC determination were performed for rifampicin (RIF) and isoniazid (INH). Genotype MTBDRplus assay, which is a molecular genetic assay based on the DNA-STRIP technology and specific gene sequencing with primers for rpoB, KatG, and mab-inhA genes were used to detect mutations associated with resistance to rifampicin and isoniazid. In comparison to other categories, most of rifampicin resistant (61.5%) and isoniazid resistant isolates (47.1%) were from patients relapsed in treatment. The genotypic profile (using Genotype MTBDRplus assay) of multi-drug resistant (MDR) isolates showed missing of katG wild type 1 (WT1) band and appearance of mutation band katG MUT2. For isoniazid mono-resistant isolates, 80% showed katG MUT1, 20% showed katG MUT1, and inhA MUT1, 20% showed only inhA MUT1. Accordingly, 100% of isoniazid resistant strains were detected by this assay. Out of 17 resistant strains, 16 had mutation bands for katG distinguished high resistance to isoniazid. The assay could clearly detect rifampicin resistance among 66.7% of MDR isolates that showed mutation band rpoB MUT3 while 33.3% of them were considered as unknown. One mono-resistant rifampicin isolate did not show rifampicin mutation bands by Genotype MTBDRplus assay, but it showed an unexpected mutation in Codon 531 of rpoB by DNA sequence analysis. Rifampicin resistance in this strain could be associated with a mutation in codon 531 of rpoB (based on molecular sequencing), and Genotype MTBDRplus assay could not detect the associated mutation. If the results of Genotype MTBDRplus assay and sequencing were combined, this strain shows hetero-resistance pattern. Gene sequencing of eight selected isolates, previously tested by Genotype MTBDRplus assay, could detect resistance mutations mainly in codon 315 (katG gene), position -15 in inhA promotes gene for isoniazid resistance and codon 531 (rpoB gene) for rifampicin resistance. Genotyping techniques allow distinguishing between recurrent cases of reinfection or reactivation and supports epidemiological studies.

Keywords: M. tuberculosis, rpoB, KatG, inhA, genotype MTBDRplus

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Authors: Saci Abdelhakim Ferkous, Khedoudja Soudani, Smail Haddadi

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This paper presents the results of a laboratory experimental study that explores the skid resistance of asphalt concrete mixtures made of local low-performance aggregates by partially replacing sand with olive mill waste (OMW). OMW was mixed with aggregates using a dry process by replacing sand with contents of 5%, 7%, 10% and 15%. The mechanical performances of the mixtures were evaluated using the Marshall and Duriez tests. A modified accelerated polishing machine was used as polishing equipment, and a British pendulum tester (BPT) was used to test the skid resistance of the samples. Finally, texture parameter analysis was performed using scanning electron microscopy (SEM) and Mountains Map software to assess the effect of OMW on the friction coefficient evolution. Using a distinct road wheel for a modified version of an accelerated polishing machine, which is normally used to determine the polished stone value of aggregates, the results showed that the addition of OMW up to 10% conferred a better skid resistance in comparison to normal asphalt concrete. The presence of olive mill waste in the mixture until 15% guarantees a gain of 22%-29% in skid resistance after polishing compared with the reference mix. Indeed, from texture parameter analysis, it was observed that there was differential wear of the lightweight aggregates (OMW) compared to the other aggregates during the polishing process, which created a new surface microtexture that had new peaks and led to a good level of friction compared to the mixtures without OMW. In general, it was found that OMW is a promising modifier for asphalt mixtures with both engineering and economic merits.

Keywords: skid resistance, olive mill waste, polishing resistance, accelerated polishing machine, local materials, sustainable development.

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Authors: Long-Shan Wu, Ming-Chen Ko, Chien-Chang Ho, Po-Fu Lee, Li-Yun Chen, Ching-Yu Tseng

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The purpose of this study was to determine whether progressive aerobic exercise intensity effects the changes in insulin resistance indicators among obese college students in Taiwan. Forty-eight obese subjects [body mass index (BMI) ≧ 27 kg/m2, aged 18-26 years old] were randomized into four equal groups (n = 12): light-intensity training group (LITG): 40-50% of their heart rate reserve (HRR); middle-intensity training group (MITG): 50-70% of their HRR; high-intensity training group (HITG): 70-80% of their HRR, and control group (CG). The aerobic exercise training program was performed 60 minutes per day on a treadmill three days/week in a training period of 12 weeks. All subjects’ anthropometric data, blood biochemical parameters, and health-related physical fitness components were measured at baseline and after 12 weeks. At baseline, all insulin resistance indicators did not differ significantly among the four groups (p > 0.05). After 12-week exercise intervention, the HITG had significantly more changes in insulin level than the MITG, LITG, and CG. Our findings suggested that a short-term aerobic exercise program can play an important role in improving insulin resistance indicators; either middle-intensity training significantly increases the insulin level, but the high-intensity exercise training program effectively improves obese college students’ insulin resistance.

Keywords: aerobic training, exercise intensity, insulin resistance, obesity

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Authors: Yoftahe Nigussie

Abstract:

This research explores the implementation of a vapor absorption refrigeration system (VARS) in mini-bus cars to enhance air conditioning efficiency. The conventional vapor compression refrigeration system (VCRS) in vehicles relies on mechanical work from the engine, leading to increased fuel consumption. The proposed VARS aims to utilize waste heat and exhaust gas from the internal combustion engine to cool the mini-bus cabin, thereby reducing fuel consumption and atmospheric pollution. The project involves two models: Model 1, a two-fluid vapor absorption system (VAS), and Model 2, a three-fluid VAS. Model 1 uses ammonia (NH₃) and water (H₂O) as refrigerants, where water absorbs ammonia rapidly, producing a cooling effect. The absorption cycle operates on the principle that absorbing ammonia in water decreases vapor pressure. The ammonia-water solution undergoes cycles of desorption, condensation, expansion, and absorption, facilitated by a generator, condenser, expansion valve, and absorber. The objectives of this research include reducing atmospheric pollution, minimizing air conditioning maintenance costs, lowering capital costs, enhancing fuel economy, and eliminating the need for a compressor. The comparison between vapor absorption and compression systems reveals advantages such as smoother operation, fewer moving parts, and the ability to work at lower evaporator pressures without affecting the Coefficient of Performance (COP). The proposed VARS demonstrates potential benefits for mini-bus air conditioning systems, providing a sustainable and energy-efficient alternative. By utilizing waste heat and exhaust gas, this system contributes to environmental preservation while addressing economic considerations for vehicle owners. Further research and development in this area could lead to the widespread adoption of vapor absorption technology in automotive air conditioning systems.

Keywords: room, zone, space, thermal resistance

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Authors: Yukinori Taniguchi, Kazuyoshi Kurita, Kohei Mizuta, Keigo Nishitani, Ryuichi Fukuda

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Tungsten carbide is widely used as a tool material in metal manufacturing process. Since tungsten is typical rare metal, establishment of recycle process of tungsten carbide tools and restore into cemented carbide material bring great impact to metal manufacturing industry. Recently, recycle process of tungsten carbide has been developed and established gradually. However, the demands for quality of cemented carbide tool are quite severe because hardness, toughness, anti-wear ability, heat resistance, fatigue strength and so on should be guaranteed for precision machining and tool life. Currently, it is hard to restore the recycled tungsten carbide powder entirely as raw material for new processed cemented carbide tool. In this study, to suggest positive use of recycled tungsten carbide powder, we have tried to fabricate a carbon based sintered steel which shows reinforced mechanical properties with recycled tungsten carbide powder. We have made set of newly designed sintered steels. Compression test of sintered specimen in density ratio of 0.85 (which means 15% porosity inside) has been conducted. As results, at least 1.7 times higher in nominal strength in the amount of 7.0 wt.% was shown in recycled WC powder. The strength reached to over 600 MPa for the Fe-WC-Co-Cu sintered alloy. Wear test has been conducted by using ball-on-disk type friction tester using 5 mm diameter ball with normal force of 2 N in the dry conditions. Wear amount after 1,000 m running distance shows that about 1.5 times longer life was shown in designed sintered alloy. Since results of tensile test showed that same tendency in previous testing, it is concluded that designed sintered alloy can be used for several mechanical parts with special strength and anti-wear ability in relatively low cost due to recycled tungsten carbide powder.

Keywords: tungsten carbide, recycle process, compression test, powder metallurgy, anti-wear ability

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Authors: O. Giorgishvili

Abstract:

For calculation of foundations one of the important characteristics is the module of deformation (E0). As we all know, the main goal of calculation of the foundations of buildings on deformation is to arrange the base settling and difference in settlings in such limits that do not cause origination of cracks and changes in design levels that will be dangerous to standard operation in the buildings and their individual structures. As is known from the literature and the practical application, the modulus of deformation is determined by two basic methods: laboratory method, soil test on compression (without the side widening) and soil test in field conditions. As we know, the deformation modulus of soil determined by field method is closer to the actual modulus deformation of soil, but the complexity of the tests to be carried out and the financial concerns did not allow determination of ground deformation modulus by field method. Therefore, we determine the ground modulus of deformation by compression method without side widening. Concerning this, we introduce a new way for determination of ground modulus of deformation by laboratory order that occurs by side widening and more accurately reflects the ground modulus of deformation and more accurately reflects the actual modulus of deformation and closer to the modulus of deformation determined by the field method. In this regard, we bring a new approach on the ground deformation detection laboratory module, which is done by widening sides. The tests and the results showed that the proposed method of ground deformation modulus is closer to the results that are obtained in the field, which reflects the foundation's work in real terms more accurately than the compression of the ground deformation module.

Keywords: build, deformation modulus, foundations, ground, laboratory research

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Authors: Rinku Varghese, S. Chandrakaran, K. Rangaswamy

Abstract:

The standard one-dimensional consolidation test is used to find the consolidation behaviour of artificially consolidated organic soils. Incremental loading tests were conducted on the clay without and with organic matter. The study was conducted with soil having different organic content keeping all other parameters constant. The tests were conducted on clay and artificially prepared organic soil sample at different vertical pressure. The load increment ratio considered for the test is equal to one. Artificial organic soils are used for the test by adding starch to the clay. The percentage of organic content in starch is determined by adding 5% by weight starch into the clay (inorganic soil) sample and corresponding change in organic content of soil was determined. This was expressed as percentage by weight of starch, and it was found that about 95% organic content in the soil sample. Accordingly percentage of organic content fixed and added to the sample for testing to understand the consolidation behaviour clayey soils with organic content. A detailed study of the results obtained from IL test was investigated. The main items investigated were (i) coefficient of consolidation (cv), (ii) coefficient of volume compression (mv), (iii) coefficient of permeability (k). The consolidation parameter obtained from IL test was used for determining the creep strain and creep parameter and also predicting their variation with vertical stress and organic content.

Keywords: consolidation, secondary compression, creep, starch

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Authors: H.Yari, M. Mohseni, Z. Ranjbar

Abstract:

In this work a typical automotive clearcoat is modified with a combination of hyperbranched polymer (HBP) and polyhedral oligomeric silsesquioxane (POSS) nanostructures to simultaneously enhance the scratch resistance and healing ability of the resulting films. Micro-scratch and healing data revealed that these goals were achieved at high loadings of modifiers. Enhanced scratch resistance was attributed to the improved elastic recovery of the clearcoats in presence of modifiers. In addition, improved healing performance due to the partial replacement of covalent cross-links with physical ones resulted from the unique globular highly branched structure of HBP and POSS macromolecules.

Keywords: automotive clearcoat, POSS building blocks scratch resistance, self-healing

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Authors: Adnan I. O. Zaid, Safwan M. A. Alqawabah

Abstract:

Review of the available literature on grain refinement of aluminum and its alloys reveals that little work is published on the effect of refiners on mechanical characteristics and wear resistance. In this paper, the effect of addition of Zr to Al grain refined by Ti+B on its metallurgical, mechanical characteristics and wear resistance both in the as cast and after extrusion condition are presented and discussed. It was found that Addition of Zr to Al resulted in deterioration of its mechanical strength and hardness, whereas it resulted in improvement of both of them when added to Al grain refined by Ti+B. Furthermore it was found that the direct extrusion process resulted in further increase of the mechanical strength and hardness of Al and its micro-alloys. Also it resulted in increase of their work hardening index, n, i.e. improved their formability, hence it reduces the number of stages required for forming at large strains in excess of the plastic instability before Zr addition.

Keywords: aluminum, grain refinement, titanium + boron, zirconium, mechanical characteristics, wear resistance, direct extrusion

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Authors: Marvin R. Tenecio

Abstract:

The analysis of "religious resistance" has been prevalent in Asian and Philippine studies. Discussions on religious resistance from a variety of perspectives are deemed as crucial turning points in the concept's ongoing development and expansion. By broadening the backdrop of religious protest between the early 1960s and the late 1980s, the researchers contend that a study examining the role carried by the Catholic Church in the upheavals against dictatorships in South Korea and the Philippines would be beneficial to the body of knowledge. This study examines a variety of historical writings about the activities occurring at that time. The researchers also compare and contrast the Catholic Church's contributions to the Korean and Philippine resistance against Park Chung-Hee and Ferdinand Marcos Sr., respectively, during the early 1960s until the late 1980s, using the lens of history from below, particularly the Pasyon and Revolution. The Catholic Church stood out against human rights abuses, promoted social justice, and mobilized the public for political reform in response to the dictatorships in South Korea and the Philippines. Even though the specific circumstances and personalities may have changed, the Church's position in both countries was vital in opposing authoritarian governments and supporting democratic movements.

Keywords: resistance, movements, catholic, church, dictatorship

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Authors: Gehan Aouf, Diala Tabbal, Abd El Rahim Sabsabi, Rashad Aouf

Abstract:

The aim of this study is to assess the viability of utilizing Municipal Solid Waste Incineration Fly Ash (MSWIFA) with Ordinary Portland cement as soil reinforcement materials for geotechnical engineering applications. A detailed experimental program is carried out, followed by analysis of results. Soil samples were prepared by adding Cement to MSWIFA-soil mix at different percentages. Then, a series of laboratory tests were performed, namely: Sieve analysis, Atterberg limits tests, Unconfined compression test, and Proctor tests. A parametric study is conducted to investigate the effect of adding the cement at different percentages on the unconfined compression strength, maximum dry density, and optimum moisture content of clayey soil-MSWIFA The variation of contents of admixtures were 10%, 20%, and 30% for MSWIFA by dry total weight of soil and 10%, 15%, and 20% for Portland cement by dry total weight of the mix. The test results reveal that adding MSWIFA to the soil up to 20% increased the MDD of the mixture and decreased the OMC, then an opposite trend for results were found when the percentage of MSWIFA exceeds 20%. This is due to the low specific gravity of MSWIFA and to the greater water absorption of MSWIFA. The laboratory tests also indicate that the UCS values were found to be increased for all the mixtures with curing periods of 7, 14, and 28 days. It is also observed that the cement increased the strength of the finished product of the mix of soil and MSWIFA.

Keywords: clayey soil, cement, MSWIFA, unconfined compression strength

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Authors: Sunil Verma

Abstract:

In today’s world non-renewable sources are depleting quickly, so there is a need to produce efficient and unconventional engines to minimize the use of fuel. Also, there are many fatal accidents happening every year during extraction, distillation, transportation and storage of fuel. Reason for explosions of gaseous fuel is unwanted autoignition. Autoignition characterstics of fuel are mandatory to study to build efficient engines and to avoid accidents. This report is concerned with study of autoignition delay characteristics of iso-octane by using rapid compression machine. The paper clearly explains the dependence of ignition delay characteristics on variation of equivalence ratios from lean to rich mixtures. The equivalence ratio is varied from 0.3 to 1.2.

Keywords: autoignition, iso-octane, combustion, rapid compression machine, equivalence ratio, ignition delay

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Authors: M. Dahiru, O. I. Enabulele

Abstract:

The research wish to investigate the occurrence of multidrug- resistant Acinetobacter, in carrot and estimate the role of carrot in its transmission, in a rapidly growing urban population. Thus, 50 carrot samples were collected from Jakara wastewater irrigation farms and analyzed on MacConkey agar and screened by Microbact 24E (Oxoid) and susceptibility of isolates tested against 10 commonly used antibiotics. Acinetobacter baumannii and A. lwoffii were isolated in 22.00% and 16% of samples respectively. Resistance to ceporex and penicillin of 36.36% and 27.27% in A. baumannii, and sensitivity to ofloxacin, pefloxacin, gentimycin and co-trimoxazole, were observed. However, for A. lwoffii apart from 37.50% resistance to ceporex, it was also resistant to all other drugs tested. There was a similarity in the resistant shown by A. baumannii and A. lwoffii to fluoroquinolones drugs and β- lactame drugs families in addition to between sulfonamide and animoglycoside demonstrated by A. lwoffii. Interestingly, when resistant similarities to different antibiotics were compared for A. baumannii and A. lwoffii as a whole, significant correlation was observed at P < 0.05 to CPX to NA (46.2%), and SXT to AU (52.6%) respectively, and high multi drug resistance (MDR) of 27.27% and 62.50% by A. baumannii and A. lwoffii respectively and overall MDR of 42.11% in all isolates. The occurrence of multidrug-resistance pathogen in carrot is a serious challenge to public health care, especially in a rapidly growing urban population where subsistence agriculture contributes greatly to urban livelihood and source of vegetables.

Keywords: urban agriculture, public health, fluoroquinolone, sulfonamide, multidrug-resistance

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