Investigation of electrical properties for cantilever-based piezoelectric energy harvester

In the present era, the renewable sources of energy, e.g., piezoelectric materials are in great demand. They play a vital role in the field of micro-electromechanical systems, e.g., sensors and actuators. The cantilever-based piezoelectric energy harvesters are very popular because of their high performance and utilization. In this research-work, an energy harvester model based on a cantilever beam with bimorph PZT-5A, having a substrate layer of structural steel, was presented. The proposed energy scavenging system, designed in COMSOL Multiphysics, was applied to analyze the electrical output as a function of excitation frequencies, load resistances and accelerations. Analytical modeling was employed to measure the output voltage and power under pre-defined conditions of acceleration and load resistance. Experimentation was also performed to determine the relationship between independent and output parameters. Energy harvester is capable of producing the maximum power of 1.16 mW at a resonant frequency of 71 Hz under 1g acceleration, having load resistance of 12 k Omega. It was observed that acceleration and output power are directly proportional to each other. Moreover, the investigation conveys that the experimental results are in good agreement with the numerical results. The maximum error obtained between the experimental and numerical investigation was found to equal 4.3%

Bidding model for sustainable projects using the traditional procurement method

The evolving concept of sustainable development introduced a new dimension to development processes and procurement routes. Consumption of natural raw materials that have fixed quantity without commensurate replacement should be a matter of concern to humanity. The need to maintain the ever growing human populace instigates the challenge that society’s developmental effort meets the demand of economic prudence, social equity and environmental conservation. This is quite daunting one, yet must be met if this planet earth and its inhabitants are not to be put in harm’s way. Sustainability in development seeks to achieve the reduction of input-output ratio yet presenting qualitative and satisfactory products to end users. The traditional procurement method (TPM) is still widely used in construction because of some advantages it offers over other methods. Contractor selection in the traditional procurement method can no longer be overlooked- being a vital process that influences project success in terms of cost, quality, function, and environmental care. Many scholars have asserted that time allowed for bidding in the TPM is little in Nigeria as such responsible for the persistent cost over-run in building construction projects. Increasing the time increases the overall project procurement period. Since market fluctuation due to other market forces is unfriendly, the goal of sustainable projects is defeated in this context. This paper seeks to enquire if the TPM remains a good base for project procurement and then modified to retain its numerous advantages over its disadvantages. Estimates from 50 samples of projects were tested using analysis of variance (ANOVA) to find if the (estimates) are reliable at times of tender. This was established and a new bidding model using the TPM proposed. The model reduced time taken to bid yet gave bidders more time to prepare their offer. Other critiques of the TPM have also been addressed in the model. This helps to achieve the goal of sustainable development and enhances TPM for built environment

Isolated gallbladder rupture following blunt abdominal trauma

The gallbladder is a relatively well‑protected organ; consequently its rupture following blunt abdominal injury is rare and usually associated with other visceral injuries. Isolated gallbladder rupture is extremely rare. We report a healthy Nigerian adult male who sustained isolated gallbladder rupture following blunt abdominal injury from riding a motor cycle (Okada). A high index of suspicion with positive bile aspirate might lead to early diagnosis. Open cholecystectomy is a safe option of treatment in a resource poor centre especially in delayed presentation and has a good outcome.Key words: Blunt abdominal trauma, gallbladder rupture, isolate

A study on the effect of chemical composition on the microstructural characteristics and mechanical performance of DP1000 resistance spot welds

This paper reports on the factors governing the mechanical properties of resistance spot welded hot dip galvanized DP1000 under tensile-shear and cross-tension loading. In particular the effects of chemical composition on the microstructural evolution and mechanical properties of DP1000 resistance spot welds are studied thoroughly, by comparison of a higher and lower carbon alloying approach. It is shown that DP1000 steel with higher carbon content attains a martensitic microstructure in the weld nugget with smaller prior austenite grains and finer block sizes. The intervariant boundary fraction analysis also reveals that DP1000 steel containing lower carbon content shows stronger variant selection as the fraction of variants belonging to the same Bain group is higher for this steel. Intervariant plane distribution also reveals that the most of intervariant boundaries for both steels terminated at or near {011} slip planes. Mechanical testing of the welds reveals that the steel with higher carbon content shows a better mechanical performance in tensile-shear test, whereas the DP steel with a lower carbon content exhibits higher maximum load of cross-tension test. The key factors controlling the mechanical response of resistance spot welds during two different mechanical tests are explored via nanoindentation, slit-milling method combined with digital image correlation and micro-cantilever bending. It is demonstrated that the strength and/or hardness of the weld nugget is the key parameter governing the tensile-shear strength of the spot welds, while the fracture toughness of the weld is the dominant parameter that determines the cross-tension strength

Previously clinically “silent” adrenal phaeochromocytoma presenting as hypovolemic shock with paradoxical hypertension

No Abstract Keywords: Phaeochromocytoma; Acute abdomen; Rupture; Hypovolemic shoc

The growth of H ii regions around massive stars: the role of metallicity and dust

This is the final version. Available from Oxford University Press via the DOI in this recordData availability: The data underlying this paper will be shared on reasonable request to the corresponding author.Gas metallicity (Z) and the related dust-to-gas ratio (fd) can influence the growth of H II regions via metal line cooling and ultraviolet (UV) absorption. We model these effects in star-forming regions containing massive stars. We compute stellar feedback from photoionization and radiation pressure (RP) using Monte Carlo radiative transfer coupled with hydrodynamics, including stellar and diffuse radiation fields. We follow a 105M⊙ turbulent cloud with Z/Z⊙ = 2, 1, 0.5, and 0.1, and fd=0.01Z/Z⊙ with a cluster-sink particle method for star formation. The models evolve for at least 1.5 Myr under feedback. Lower Z results in higher temperatures and therefore larger H II regions. For Z ≥ Z⊙, RP (Prad) can dominate locally over the gas pressure (Pgas) in the inner half-parsec around sink particles. Globally, the ratio of Prad/Pgas is around 1 (2 Z⊙), 0.3 (Z⊙), 0.1 (0.5 Z⊙), and 0.03 (0.1 Z⊙). In the solar model, excluding RP results in an ionized volume several times smaller than the fiducial model with both mechanisms. Excluding RP and UV attenuation by dust results in a larger ionized volume than the fiducial case. That is, UV absorption hinders growth more than RP helps it. The radial expansion velocity of ionized gas reaches +15 km s−1 outwards, while neutral gas has inward velocities for most of the runtime, except for 0.1 Z⊙ that exceeds +4 km s−1. Z and fd do not significantly alter the star formation efficiency, rate, or cluster half-mass radius, with the exception of 0.1 Z⊙ due to the earlier expulsion of neutral gas.European Union Horizon 202

Laparoscopic Cholecystectomy: A 15-years Experience at a Single Centre, Wad Medani, Sudan

No Abstract

Hasil Unplag_Effect of Angle of Attack on Airfoil NACA 0012 Performance

Airfoil is an aerodynamic form intended to produce a lift force with the smallest drag force. When an airfoil is passed through a fluid flow that causes interaction between the air flow and the surface, variations in velocity and pressure will occur along the top and bottom surfaces of the airfoil, as well as the front and back of the airfoil. The difference in pressure between the upper and lower surface of the airfoil is what causes the resultant force in the direction perpendicular to the direction of fluid flow, this force is called the lift force (lift). In this experiment NACA 0012 airfoil experiments have been carried out using simple wind tunnel. Experiments were conducted with the aim to determine the effect of the angle of attack on the performance of the NACA 0012 airfoil which then analyzed the lift force of the NACA 0012 airfoil. The variation of the angle of attack used was 0 °, 3 °, 6 °, 9 °, 12 °, and 15 ° and used wind speed of 21.5 m / s. The greatest lift force is obtained at an angle of attack of 9 ° with a value of 0.981 while the largest lifting coefficient with a value of 0.106. The greater the angle of attack the greater the airfoil lift force, but for symmetrical airfoil stall at an angle that is too larg

Peer Review_2 Artikel Pengaruh Penambahan HHO terhadap Kinerja dan Ionisasi Pembakaran Motor Bensin

This aim of this research was to conduct the effect of HHO which injected into the combustion chamber through the intake manifold of the gasoline four-stroke motorcycle engine. HHO is a mixture of hydrogen and oxygen was produced by water electrolysis process.The experiments were carried out by using the HHO generatorin intake manifold to produced HHO gas, which injected into the combustion chamber. The HHO gas injection was varied of 0 ml/s, 0.75 ml/s, 1.5 ml/s, 2.25 ml/s and 3 ml/s based on the engine shaft revolution (rpm). The engine shaft revolutions were also varied at 1700 rpm, 2200 rpm, 2700 rpm, 3200 rpm, 3700 rpm, and 4200 rpm. The engine performance (power output effectively, SFC, and thermal efficiency), the ionization combustion (burning voltage and burning time) and exhaust gas emissions (HC and CO) were investigated. The results show that the additionof the HHO gascould improve the performance of the gasoline four-stroke engine. The effective of power out-put and thermal efficiency increase as increase the HHO injection.The specific fuel consumption (sfc) was also decreases as increases the HHO injection. The ionization combustion much better, which the voltage products of combustion increase and combustion time decrease as increase the HHO injection. The addition of HHO gas was also improved the quality of exhaust gas emission which are reduce the content of CO and HC gases due tothe HHO enhance the combustion process. The hydrogen gas has a high diffusivity which can improve of the fuel mixing, turbulence and homogeneity. The hydrogen gas has the flamehigh faster than gasoline, therefore its decrease the burning time as increase the HHO injection