Review Of Experimental Investigations Research Articles

A Review of Experimental Investigations into the Time Evolution of Low-Pressure Capacitively Coupled Plasmas in Their Early Stages of Development

A Review of Experimental Investigations into the Time Evolution of Low-Pressure Capacitively Coupled Plasmas in Their Early Stages of Development

State of the Art on Two-Phase Non-Miscible Liquid/Gas Flow Transport Analysis in Radial Centrifugal Pumps Part B: Review of Experimental Investigations

This paper aims to summarize the results of several experimental investigations regarding two-phase liquid–gas flows in radial centrifugal pumps. The main objective is to combine the corresponding experimental results and collect the obtained knowledge to provide a better understanding of this configuration. The simultaneous transport of the two phases, the phase segregation, and the regions of safe or critical pump performance were described for a wide variety of pump configurations. This review covers single- and two-phase pumping conditions, performance degradation, pump breakdown, performance hysteresis, different flow regimes, flow regime maps, flow instabilities, and surging. This manuscript also considers the influence of employing different pump configurations on pump performance and flow regimes. This includes comparisons between closed and semi-open impellers, standard and increased tip clearance gaps, and running the pump with and without an inducer. Many of the results discussed have been published in a series of research papers. They were all collected, summarized, and compared systematically in the present review.

Review of experimental investigations on seismic performance of precast segmental bridge columns in seismic regions

Due to the fast construction and low interference, precast segmental bridge columns have gained increasing attention for use in non-seismic regions. However, their applications in seismic areas remain scarce due to their ambiguous dynamic performance. To estimate the seismic performance of PSBCs, existing quasi-static cyclic tests and shaking table tests are gathered and reviewed in this study. According to the structural details and material property at the joints, the PSBCs are categorized as 11 types based on the connection type, namely grouted splice sleeve couplers (GSSCs), grouted corrugated duct connections (GCDCs), wet joint connections (WJCs), mechanical bar splice connections, socket connections (SCs), unbonded post-tensioned tendon connections (UPTCs), partial precast columns (PPCs), hybrid connections (HCs), high-strength steel bars (HSBs), high-performance concrete (HPC), and external dissipators (EXDs). Based on the experimental results, the failure reason of each connection types are discussed and the effective structural details are suggested. And also, the PSBCs are divided into those with ductile and resilient connections according to the damage levels, residual drift ratios, displacement ductility coefficients, equivalent viscous damping ratios and effective stiffness parameters. With the achievements in this research, the application of PSBCs is expected to be promoted in medium-to-high seismic regions.

Metals and metal ions release from metallic implants in the animal body models: A review of experimental investigations

Metals and metal ions release from metallic implants in the animal body models: A review of experimental investigations

Metals and metal ions release from metallic implants in the animal body models: A review of experimental investigations

All non-noble metals and alloys will release metallic species into the body. This raises the issue of amount and fate, i.e. transport and storage, of these metal dissolution products. No metal or alloy is completely inert in vivo. Metallic transfer from implants does not stop at surrounding tissues, and metallic elements may be transferred by proteins to become lodged in organs far from the implant. The use of metallic biomaterials in the medical implant devices has become increasingly prevalent over the past few decades. Metals and metal ions release from metallic materials; titanium and titanium and its alloys, nickel-titanium alloys, cobalt-chromium alloys, and magnesium-based alloys implanted into the human body is becoming a major cause of concern. The development of reliable experimental models for the clinical use of biomaterials and in predicting implant success or failure is becoming increasingly important in attaining adequate health and safety conditions. Animal models provide important biomaterial knowledge that eventually leads to the development of more effective clinical treatments of diseases in both humans and animals; therefore, acting as a bridge between In vitro studies and in vivo clinical trials. The most commonly used laboratory animals have turned out to be rats, mice, and rabbits, probably because they are cheaper and easy to handle. In addition, cattle, primates, sheep, swine and guinea pigs are used by researchers in a progressively decreasing order. The present review reported the results of In vitro and in vivo experimental investigations on the release of metallic traces in the biological fluids, tissues and different inner organ tissues resulting from the implantation of the small metallic implants in the animals.

Свойства поверхности конструкционных материалов в области штрих-кода, сформированного под воздействием лазерного излучения

A review of experimental investigations of changes in the structure and properties of the surface and near-surface layers of various materials (steels, metal alloys, ceramics and graphite) in the area of a barcode applied by continuous laser radiation and short (nanosecond) and ultrashort (femto- and picosecond) laser pulses.

Effect of Alkali Resistant Glass Fiber on Performance of Cement Concrete - A Review of Experimental Investigations

Cement concrete, a universally accepted construction material is enough strong in compression but weak in tension with limited ductility and therefore its resistance to cracking is low attributed to the inherent presence of micro-internal cracks. In order to improve its resistance to cracking, and post peak response, alkali-resistant glass fiber (ARGF) as an additive is one of the options. This is added in certain percentage during mixing and the concrete is generally called alkali-resistant glass fiber reinforced concrete (ARGFRC). This paper presents review of the experimental research works carried out on use of type with regards to aspect ratio and quantity of ARGF in cement concrete. Type and quantity both influence the properties of fresh and hardened ARGFRC. The dosage effect with quantity of the fiber on fresh concrete such as workability, and mechanical performance, seismic vulnerability evaluation, microstructural analysis, durability aspects on hardened concrete have been reviewed. It is found that alkali-resistant glass fiber together with silica fume can be utilized to enhance the toughness and load carrying capacity and improve the stiffness of the composite concrete.

Review of Experimental Research on Supercritical and Transcritical Thermodynamic Cycles Designed for Heat Recovery Application

Supercritical operation is considered a main technique to achieve higher cycle efficiency in various thermodynamic systems. The present paper is a review of experimental investigations on supercritical operation considering both heat-to-upgraded heat and heat-to-power systems. Experimental works are reported and subsequently analyzed. Main findings can be summarized as: steam Rankine cycles does not show much studies in the literature, transcritical organic Rankine cycles are intensely investigated and few plants are already online, carbon dioxide is considered as a promising fluid for closed Brayton and Rankine cycles but its unique properties call for a new thinking in designing cycle components. Transcritical heat pumps are extensively used in domestic and industrial applications, but supercritical heat pumps with a working fluid other than CO2 are scarce. To increase the adoption rate of supercritical thermodynamic systems further research is needed on the heat transfer behavior and the optimal design of compressors and expanders with special attention to the mechanical integrity.

POWER LOSSES OF GEAR SYSTEMS

This paper provides a review of experimental investigations and available models of gear load-independent power losses (windage losses, churning losses and air-oil pocketing power losses) for spur, helical, and bevel gears. The aim of the review is to provide a comprehensive compilation of published information on gear load-independent power losses to assist gearbox designers in identifying relevant experimental and modeling information. While it is clear from the review of published work that the rotational speed, gear geometrical parameters, degree of confinement, and density of the fluid surrounding the gear are important, the degree of effect and general solutions for reducing power loss are less clear. The motivation for this is that for some applications, this power loss can be a significant component, particularly lightly loaded high-speed applications.

Review of Experimental Investigations in Friction Welding Technique

<p>Friction welding is a solid state welding processes in which the weld is obtained by the heat generated due to forging and friction. Now a day’s eco-friendly joining of dissimilar materials is the need of the industries. The advantages of friction welding process are reduction in production time and cost saving. Friction welding is classified into two types. One type is Inertia drive friction welding and the other is Continuous drive friction welding. In continuous drive friction welding one of the work pieces is held stationary while the other is held for a certain rotating speed. The two work pieces are brought together under certain friction pressure for a<br />certain period of time known as friction time. Then, the rotation is stopped and upset pressure is applied for a certain upset time. Then, the spindle is disengaged and the component is unloaded. In Inertia drive friction welding one part is held stationary while the other is clamped in the chuck which is attached to the flywheel. The flywheel and chuck is rotated for a certain seed to store a predetermined energy. In this paper, review of friction welding on different materials and their weld ability has been discussed in brief.</p>

A review of experimental investigations and assessment methods for masonry arch bridges

Masonry arch bridges constitute a significant proportion of European road and rail infrastructures. Most of them are well over 100 years old and are supporting traffic loads many times above those originally envisaged. The inherent variation in their constituent materials, the traditional design criteria and methods used for their construction, their deterioration over time caused by weathering processes and the development of other defects, significantly influence the mechanical response of these historic structures. A deep understanding on the numerous factors that affect the structural behaviour of masonry arch bridges and on the analysis methods to assess the life expectancy of such bridges and inform maintenance and strengthening strategies is essential. This paper provides a critical review of the experimental studies that have been carried out and of the assessment approaches that have been developed in the last three decades to these aims. The current knowledge is established and areas of possible future research work are identified, with the aim of providing students and researchers, asset managers and bridge owners, and practitioners with a guidance for research activities and maintenace strategies.

Contact mechanics and tribology of polymer composites

ABSTRACTWe review contact mechanics with emphasis on the rheological (time dependent) properties of polymers and their relations to surface roughness, material properties, and friction as well as wear behavior of rubbing polymer surfaces. The main concept of polymer mechanics related to tribology consists of three basic elements involved in friction: deformation resulting in the real area of contact of rough surfaces, contact adhesion, and shear and rupture of materials in the contact during the sliding friction. The results of classical work are included, which addresses the real contact area calculation and the description of adhesion interaction between rough surfaces. A brief review of experimental investigations concerning the surface characterization by means of bearing curves, the intermolecular force interaction using the adhesion parameter, the effect of temperature on the real contact area, the formation of transferred polymer film during friction, and tribological behavior of ultrathin polymer layers are presented and their implications discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39870.

Review of experimental investigations into the design, performance and optimization of the Savonius rotor

The Savonius rotor is a drag-based vertical axis wind turbine and is used as an alternative source in small-scale energy generation. Design simplicity, low-cost, easy installation, good starting ability, relatively low operating speed and independent to wind directions are the main advantages of this rotor. However, because of its low efficiency and high negative torque produced by the returning blade, this rotor concept rarely gained popularity. Over the last few decades, although a number of investigations around the world have reported performance gains of the Savonius rotor, the available technical design is still not able to fulfill the demand of efficient small-scale wind energy converter at low wind speeds. Until now, various design changes have been proposed to meet a growth in power output through optimization of influencing variables like aspect ratio, overlap ratio, blade material, and so forth. Investigations have also been carried out by installing additional devices like curtain design, deflector plate, nozzle and ducts, multi-staging, guide-box tunnel and windshields. Installation of these devices considerably reduced the negative torque as well as improved the starting performance of the rotor. As a result, the power output of the rotor is also improved. Several researchers have reported increased power coefficients for various rotor designs based on their different testing parameters. Power coefficients for the conventional Savonius rotors have been mostly reported in the range of 0.12–0.18 and by optimizing its design, it can reach as high as 0.38. This article attempts to discuss the various influencing parameters as well as the augmentation techniques. This would offer an overall idea on the progress that has taken place to improve the design and performance of the Savonius rotor.

Review of Experimental Investigations on Compressibility of Arteries and Introduction of a New Apparatus

Arterial tissue incompressibility is a common notion used in numerical simulations and analytical studies. However, only a few experimental investigations have been performed to characterize arterial tissue incompressibility. Such studies have used various approaches, ranging from the initial purely mechanical measurements in 1954 to the more recent image-based analyses (2004). The results of these studies are rather diverse because different arteries have been tested (human/dog/mouse, carotid/pulmonary/iliac). This has therefore made accurate comparisons between studies challenging. In the first part of this report, a review of the experimental investigations on the compressibility of arteries is presented, with particular focus on the test rigs that have been used. In the second part of this report, a novel simple apparatus to test samples under physiological or supra-physiological conditions is described. Recommendations for a testing procedure are also provided. Finally, preliminary results on porcine renal arteries indicate significant levels of compressibility are possible (>10 %), thereby suggesting the need for further investigation.

Electrodeposition of different types of tungsten cathode deposits from ionic melts

A review of experimental investigations of electrochemical deposition of tungsten from ionic melts is presented. The electrolytes used are systematized depending on the structure of deposits.

Sloshing of liquids in partially filled tanks - a review of experimental investigations

Liquid sloshing constitutes a broad class of problems of great practical importance with regard to the safety of liquid transportation systems, such as tank trucks on highways, liquid tank carriages on rail roads, ocean going vessels and propellant tanks in liquid rocket engines. The present work attempts to give a review of some selected experimental investigations carried out during the last couple of decades. This paper highlights the various parameters attributed to the cause of sloshing followed by effects of baffles, tank inclination, magnetic field, tuned liquid dampers, electric field etc. Further, recent developments in the study of sloshing in micro and zero gravity fields have also been reported. In view of this, fifteen research articles have been carefully chosen, and the work reported therein has been addressed and discussed. The key issues and findings have been compared, tabulated and summarized.

A review of experimental investigations on thermal phenomena in nanofluids

Nanoparticle suspensions (nanofluids) have been recommended as a promising option for various engineering applications, due to the observed enhancement of thermophysical properties and improvement in the effectiveness of thermal phenomena. A number of investigations have been reported in the recent past, in order to quantify the thermo-fluidic behavior of nanofluids. This review is focused on examining and comparing the measurements of convective heat transfer and phase change in nanofluids, with an emphasis on the experimental techniques employed to measure the effective thermal conductivity, as well as to characterize the thermal performance of systems involving nanofluids.

ChemInform Abstract: The Local Magnetic States in Spin-Ordered Amorphous and Crystalline Alloys

The review of experimental investigations of local magnetic states is given for three types of spin ordered materials: the cubic Laves phases with C15 structure, multicomponent heterophase alloys of Nd-R-Fe-M-B type and Heusler alloys. To obtain information on local magnetic states several kinds of experimental techniques were used: measurements of nuclear specific heat at T<1K. Mossbauer effect, nuclear spin-echo. The obtained results are treated in terms of several theoretical models and some essential parameters of itinerant and localized electron spectra are estimated and discussed.

Gear Windage: A Review

The efficiency of power and propulsive systems is increasingly being targeted as a means of reducing environmental impact. This has caused a renewed interest in industry in the losses associated with meshing gears. Gearbox efficiency varies from 98% to 99% for the best designed high power applications, but that can still equate to losses in megawatts. There are different mechanisms for losses that have been identified within gearboxes; these are meshing losses, bearing losses, windage losses, and churning losses. Depending on the application, the relative importance of these mechanisms varies. This paper reviews information on windage power loss. The motivation for this is that for some applications, this power loss can be a significant component, particularly lightly loaded high-speed applications. For instance, within some aeroengines, gears are mounted internally within bearing chambers. The component of windage power loss becomes significant in this case, and the flows associated with windage power loss have a significant impact on the amount of heat transferred to the oil within the chamber, which is a critical design consideration. This paper provides a review of experimental investigations and available models of gear windage power loss for spur, helical, and bevel gears. The aim of the review is to provide a comprehensive compilation of published information on windage power loss to assist gearbox designers in identifying relevant experimental and modeling information. While it is clear from the review of published work that the rotational speed, gear geometrical parameters, degree of confinement, and density of the fluid surrounding the gear are important, the degree of effect and general solutions for reducing power loss are less clear.

Severe Slugging in Flexible Risers: Review of Experimental Investigations and OLGA Predictions

Flexible risers are key components of floating production systems, particularly in harsh environmental conditions where the riser must deal with substantial vessel motion. Liquid slugging in flexible risers often causes severe operational problems for the downstream production system. To avoid such costly delays, it would be desirable to predict severe slugging behavior in flexible risers using experiments and transient codes. This article details the basic mechanisms and general characteristics of severe slugging in a pipeline-riser system. It also tries to present the research studies that have been carried out on severe slugging in flexible risers in two parts; experiments on different flexible riser configurations, and existing OLGA code predictions.