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2007 Choice Outstanding Academic Title Winner of the Passing the Torch Award from the Center for Lesbian and Gay Studies It has been called sperm, semen, seed, cum, jizz, spunk, gentlemen's relish, and splooge. But however the “tacky, opaque liquid that comes out of the penis” is described, the very act of defining “sperm” and “semen” depends on your point of view. For Lisa Jean Moore, how sperm comes to be known is based on who defines it (a scientist vs. a defense witness, for example), under what social circumstances it is found (a doctor’s office vs. a crime scene), and for what purposes it will be used (in vitro fertilization vs. DNA analysis). Examining semen historically, medically, and culturally, Sperm Counts is a penetrating exploration of its meaning and power. Using a “;follow that sperm” approach, Moore shows how representations of sperm and semen are always in flux, tracing their twisting journeys from male reproductive glands to headline news stories and presidential impeachment trials. Much like the fluid of semen itself can leak onto fabrics and into bodies, its meanings seep into our consciousness over time. Moore’s analytic lens yields intriguing observations of how sperm is “spent” and “reabsorbed” as it spurts, swims, and careens through penises, vaginas, test tubes, labs, families, cultures, and politics. Drawn from fifteen years of research, Sperm Counts examines historical and scientific documents, children's “facts of life” books, pornography, the Internet, forensic transcripts and sex worker narratives to explain how semen got so complicated. Among other things, understanding how we produce, represent, deploy and institutionalize semen-biomedically, socially and culturally-provides valuable new perspectives on the changing social position of men and the evolving meanings of masculinity. Ultimately, as Moore reveals, sperm is intimately involved in not only the physical reproduction of males and females, but in how we come to understand ourselves as men and women.

Originally published in 2006, this is a comprehensive and definitive account of the human male gamete. The volume summarizes many unique and revealing characteristics of the sperm cell. It provides a detailed overview of human sperm production, maturation and function, and looks at how these processes affect and influence fertility, infertility and ART. The volume thus provides a detailed review of the most important research and developments, augmented with pertinent references. This book will appeal to all practitioners and scientists in reproductive medicine and in particular to clinical scientists, graduate and post-graduate scientists, and laboratory personnel.

In recent years, turbochargers have gained importance in the automotive industry, locomotive, and marine applications powered by diesel engines. Also, they are widely implemented in aerospace applications to enhance the engine's performance. The lightweighted turbochargers are implemented in aerospace and automotive industries having a rotational speed above 150,000 rpm; meanwhile, the turbochargers implemented in marine and locomotive applications are heavily sized, with rotational speeds around 30,000 rpm. By recovering waste energy from exhaust gases, the turbocharger provides higher inlet air pressure and mass to the engine and, in turn, boosts engine efficiency and reduces emissions. Bearings such as floating ring bearings, rolling element bearings, hydrodynamic bearings and gas foil bearings are the commonly supported bearings for turbochargers which can operate at higher speeds and are strongly nonlinear. However, while running, the rotor vibrates at sub-synchronous frequencies due to fluid instabilities. Instabilities occur in rotors mainly because of unbalanced, whirl, and whip phenomena of oil. Hence, along with the nonlinear and stability analysis, the thermo-mechanical effects must analyze thoroughly for better performance and improvement in the turbocharger's efficiency. The proposed study thoroughly reviews various analyses for a turbocharger rotor system assisted on the bearings mentioned above with different operating conditions. It explains the influence of the thrust bearing on the turbocharger dynamics. Further, the report includes additional guidelines on research topics that must explore extensively in the upcoming years.

Despite enormous research, material, and manufacturing advancements in bearings, these continue to fail in critical aerospace applications. Material and processing aspects of bearing, which are often secondary, then become the central theme of investigation in place of a systemic and holistic view. Therefore, unlike conventional failure analysis, the present review critically examines potential issues in functionality, operation, unusual assembly configurations resulting in opposing inputs to the rolling elements, high DN (diameter × rpm) situations, distress due to slip, skid, and fatigue. Contra-rotating bearing can alleviate the effect of opposing inputs in aeroengine bearings where both the races rotate. It covers both state-of-the-art and conventional concepts. A brief on bearing materials, both conventional and unconventional, is also presented. Various techniques for monitoring bearing health and fault diagnosis are outlined. Life testing of bearing is mandatory to improve the design, material selection, manufacturing, and analysis. While prediction of the B10 life of bearings using Weibull analysis is more prevalent among industries, aerospace industry prefers B1.0 life. A brief on future possibilities is also presented. The present review aims to bring an application perspective on aerospace bearings to prevent their failures and enhance life.

Electrical bearing currents may disturb the performance of the bearings via electro-corrosion if they surpass a limit of ca. 0.1 to 0.3 A/mm2. A continuous current flow, or, after a longer time span, an alternating current or a repeating impulse-like current, damages the raceway surface, leading in many cases to a fluting pattern on the raceway. Increased bearing vibration, audible noise, and decreased bearing lubrication as a result may demand a replacement of the bearings. Here, an electrically corroded axial ball bearing (type 51208) with fluting patterns is investigated. The bearing was lubricated with grease lubrication and was exposed to 4 A DC current flow. It is shown that the electric current flow causes higher concentrations of iron oxides and iron carbides on the bearing raceway surface together with increased surface roughness, leading to a mixed lubrication also at elevated bearing speeds up to 1500 rpm. The “electrically insulating” iron oxide layer and the “mechanically hard” iron carbide layer on the bearing steel are analysed by WLI, XPS, SEM, and EDS. White Light Interferometry (WLI) is used to provide an accurate measurement of the surface topography and roughness. X-ray Photoelectron Spectroscopy (XPS) measurements are conducted to analyze the chemical surface composition and oxidation states. Scanning Electron Microscopy (SEM) is applied for high-resolution imaging of the surface morphology, while the Focused Ion Beam (FIB) is used to cut a trench into the bearing surface to inspect the surface layers. With the Energy Dispersive X-ray spectrometry (EDS), the presence of composing elements is identified, determining their relative concentrations. The electrically-caused iron oxide and iron carbide may develop periodically along the raceway due to the perpendicular vibrations of the rolling ball on the raceway, leading gradually to the fluting pattern. Still, a simulation of this vibration-induced fluting-generation process from the start with the first surface craters—of the molten local contact spots—to the final fluting pattern is missing.

The effect of variable DC bearing current amplitude, bearing current polarity, mechanical force, rotation speed, bearing temperature, and number of the balls on the fluting in an axial ball bearing type 51208 is investigated under DC currents. The results are obtained from two different test setups with two different lubricants (mineral-oil-based grease and polyglycol oil). The speed varies between 100 rpm and 2000 rpm, the axial bearing force between 200 N and 2400 N, the DC current amplitude between 0.5 A and 20 A, the bearing temperature between 29 °C and 80 °C, the number of steel balls per bearing between 3 and 15, and the test duration between 6 h and 168 h. The results show that with a higher bearing current density and/or a higher bearing speed, a lower bearing force and/or a lower bearing temperature, a bigger number of roller elements, but also at a negative polarity of a DC electric bearing current, the occurring of fluting is more probable and occurs at an earlier stage of operation.

The development of air bearing demands further research and certain guidance. The previous technical reviews focused on specific aspects, while bibliometric analysis employed in this paper gave a general overview on air bearing field and provided clearer research interest and development trend. The publications in the field of air bearing from 1990 to 2017 based on the Science Citation Index Expanded (SCIE) database were analyzed from the aspects of countries, institutions, research areas, journals, authors, keywords, reviews, and high cited papers, implemented by some representative and convincing indicators. The result showed that the USA held the dominant position in this field, followed by Japan and China. The University of California System held the top position in terms of total papers and h-indexes. It had shown a multi-disciplinary development trend of air bearings from the aspect of research area. Tribology related journal took high ranking of the list, in which “Journal of Tribology-Transactions of the ASME” ranked first. Bogy, D. B., made most contributions to the air bearing field, with the highest total citations and h-index. Thermal effects, foil bearing, dynamic analysis, and active compensation were hotspots. Reynolds equation, stability, optimization, load-carrying capacity, foil bearings, and aerostatic bearings were potential directions that might have greater opportunities for improvement. The improvement of air bearing requires common progress in multiple aspects.

Oil-lubricated foil bearings have become one of the preferred choices for supporting high-speed rotor systems due to their characteristics, such as low friction losses and excellent adaptability. This study presents an efficient and accurate solution for calculating the stability of multi-foil oil-lubricated foil bearings with back springs. Based on the static and dynamic characteristics solved by the finite difference method, a nonlinear oil film force model considering multiple parameters was established through polynomial fitting. The dynamic model of the bearing-rotor system was established using the finite element method, and the Newmark method was employed to solve the dynamic response for the analysis of bearing stability. The bearing test rig was designed and constructed to assess the vibration characteristics. The stability solution method proposed in this paper eliminates the calculation process of oil film force in traditional methods, significantly improving computational efficiency. The research demonstrates that increasing the bearing clearance and length results in a sharp decrease in the instability threshold speed. The experimental results confirm the validity of the theoretical model, and the instability phenomenon induced by the dominance of low-frequency components is observed at 125,358 r/min.

When a magnetic bearing is used in the design of a high-speed motor, no friction and wear occur because of the principle of magnetic levitation; however, the size of the entire system increases. An integrated magnetic bearing motor is a motor with a magnetic bearing inserted inside the rotor that can minimize the increase in the size of the entire system. In this study, a method to reduce the bearing force ripple and torque ripple of an integrated magnetic bearing motor through parameters for a Halbach array and permanent magnet tapering is proposed. When designing an integrated magnetic bearing motor, because the magnetic bearing is located inside the rotor, the influence of the magnetic flux of the rotor and stator on the magnetic flux of the magnetic bearing should be minimized. By combining the magnetic fluxes of the magnetic bearing, rotor, and stator at the rotor back yoke, magnetic saturation occurs, and the performance of the bearing force and torque ripples decreases. The bearing force and torque according to the Halbach array and permanent magnet tapering were analyzed using finite element analysis. The average bearing force and torque were maximized, and the ripple was minimized through the rotor parameters. Thus, the validity of the main design variables selected to improve the output characteristics was confirmed.

The rotor misalignment fault, which occurs only second to imbalance, easily occurs in the practical rotating machinery system. Rotor misalignment can be further divided into coupling misalignment and bearing misalignment. However, most of the existing references only analyze the effect of coupling misalignment on the dynamic characteristics of the rotor system and ignore the change of bearing excitation caused by misalignment. Based on the above limitations, a five degrees of freedom nonlinear restoring force mathematical model is proposed, considering misalignment of bearing rings and clearance of cage pockets. The finite element model of the rotor is established based on the Timoshenko beam element theory. The coupling misalignment excitation force and rotor imbalance force are introduced. Finally, the dynamic model of the ball bearing-coupling-rotor system is established. The radial and axial vibration responses of the system under misalignment fault are analyzed by simulation. The results show that the bearing misalignment significantly influences the dynamic characteristics of the system in the low-speed range, so bearing misalignment should not be ignored in modeling. With the increase of rotating speed, rotor imbalance and coupling misalignment have a greater impact. Misalignment causes periodic changes in bearing contact angle, radial clearance, and ball rotational speed. It also leads to reciprocating impact and collision between the ball and cage. In addition, misalignment increases the critical speed and the axial vibration of the system. The results can provide a basis for health monitoring and misalignment fault diagnosis of the rolling bearing-rotor system.