bluuebunny/crossref_metadata_2025 huggingface dataset:
Seawater recirculation through subducting sediments sustains a deeply buried population of sulfate‐reducing bacteria
Authors: Cox Toni L. , Gan Han Ming , Moreau John W.
Published: November 2018

Subseafloor sulfate concentrations typically decrease with depth as this electron acceptor is consumed by respiring microorganisms. However, studies show that seawater can flow through hydraulically conductive basalt to deliver sulfate upwards into deeply buried overlying sediments. Our previous work on IODP Site C0012A (Nankai Trough, Japan) revealed that recirculation of sulfate through the subducting Philippine Sea Plate stimulated microbial activity near the sediment–basement interface (SBI). Here, we describe the microbial ecology, phylogeny, and energetic requirements of population of aero‐tolerant sulfate‐reducing bacteria in the deep subseafloor. We identified dissimilatory sulfite reductase gene (dsr) sequences 93% related to oxygen‐tolerant Desulfovibrionales species across all reaction zones while no SRB were detected in drilling fluid control samples. Pore fluid chemistry revealed low concentrations of methane (<0.25 mM), while hydrogen levels were consistent with active bacterial sulfate reduction (0.51–1.52 nM). Solid phase total organic carbon (TOC) was also considerably low in these subseafloor sediments. Our results reveal the phylogenetic diversity, potential function, and physiological tolerance of a community of sulfate‐reducing bacteria living at ~480 m below subducting seafloor.
Does venture capital spur innovation or the other way around? Evidence on the significance of investment timing from China
Authors: Lin Xiao , Xu Wei , Zhang Baiping , Yang Fan
Published: November 2018

This paper explores the interaction between venture capital and innovation in China. We focus on the difference between early, development, and expansion stages of innovation firms when they receive their first installment of venture capital. Using ordinary least squares (OLS), switching regression model and counterfactual comparison, we find that selection effect exists in all three stages, suggesting that established innovation capacity increases the possibility of innovation firms to receive venture capital. Further, the selection effect is most profound in the development stage. The treatment effect, the combined effect of financial role and value‐added service, plays an important role in promoting innovation in all three stages. However, the mechanisms of the effect vary greatly across the early, development, and expansion stages. The financial role of venture capital does not influence innovation in the early stage, but promotes innovation in the development stage, and restrains innovation in the expansion stage. Value‐added service promotes innovation in the early and expansion stages, and whether it influences innovation in the development stage needs further study.
Nucleus‐localized adiponectin is survival gatekeeper through miR‐214‐mediated AIFM2 regulation
Authors: Cho Junkwon , Teshigawara Rika , Kameda Masahiro , Yamaguchi Shinpei , Tada Takashi
Published: November 2018

Adiponectin secreted from adipocytes into plasma has anti‐aging, anti‐obesity and anti‐inflammation effects. Here, we detected intracellular adiponectin localized in the nuclei of human and mouse pluripotent stem cells, mouse germ cells and some somatic cells. Nucleus‐localized (Nu) adiponectin protein is characterized by an N‐terminal truncated monomer form in a native state, compared with intact multimer forms of cytoplasm‐localized (Cy) adiponectin protein. Doxycycline‐induced over‐expression of ADIPONECTIN caused cell death in human and mouse Nu‐type pluripotent stem cells. Genome‐wide gene expression analysis indicated that apoptosis by ADIPONECTIN over‐expression was induced in accompany with upregulation of AIFM2 and MEG3. Upregulation of AIFM2 and MEG3 and down‐regulation of miR‐214‐3p verified by qPCR analyses after ADIPONECTIN over‐expression indicated that the MEG3/miR‐214/AIFM2 pathway played a role in the apoptotic cell death of pluripotent cells. Adiponectin‐induced cell death was rescued by the treatment with miR‐214‐3p mimic. Global data analysis shows that Nu adiponectin has a role in microRNA‐mediated post‐transcription regulation, cell–cell interactions and chromatin remodeling as a survival gatekeeper.
Asset or Liability: Transnational Links and Political Participation of Foreign‐Born Citizens in Taiwan
Authors: Cheng Isabelle , Momesso Lara , Fell Dafydd
Published: November 2018

Viewed as outsiders clinging onto links with their country of origin, immigrants do not often feature positively in electoral politics in their host society. Challenging this conventional view, this article examines how immigrants make use of their transnational ties to foster their political participation in the host state. This exploration is conducted through our study of the political participation of Vietnamese and Chinese immigrants in Taiwan. Our research finds that transnational ties are politicized by the mainstream political parties. However, such politicization does not necessarily restrict immigrants’ agency and their sociopolitical space for political participation. Their transnational ties constitute a dynamic sociopolitical field in which these maintained connections are acted upon and give rise to a variety of strategies for responding to issues affecting their interests.
Antilisterial and antistaphylococcal activity of a Lactococcus lactis strain isolated from Brazilian fresh Minas cheese
Authors: Costa Ana Carolina Cabral Carvalhaes , Pereira Aline Neves , Silva Adrielle Cristina de Andrade e , da Silva Flávio Alves , Ribeiro Keyla de Oliveira , Torres Ieda Maria Sapateiro , De Martinis Elaine Cristina Pereira , Alves Virgínia Farias
Published: November 2018

Lactococcus lactis QMF 11, isolated from Brazilian fresh cheese, produces bacteriocin like inhibitory substances (bac+). To evaluate L. lactis QMF11 possible application on biopreservation systems of dairy food, co‐inoculation studies were performed in pasteurized milk (8 °C, 10 days) targeting the inhibition of Listeria monocytogenes ATCC 7644 or Staphylococcus aureus ATCC 25923. Lactobacillus sakei ATCC 15521 was used as a negative control for bacteriocin production (bac−). L. monocytogenes and S. aureus reached 8 log CFU ml−1 and 5.4 log CFU ml−1 in monoculture, respectively, compared to <2.3 log CFU ml−1 and 4.7 log CFU ml−1 in co‐culture with L. lactis QMF 11. Instead, in the presence of the bac−, L. monocytogenes population reached 7.3 log CFU ml−1 and S. aureus populations 5.5 log CFU ml−1. These results indicate that L. lactis QMF11 may have potential for be use as biopreservative culture in dairy products, mainly because of its antilisterial activity.

Practical applications

There is a renewed interest in the use protective bacterial cultures or their metabolites to guarantee the microbiological safety and to extend the shelf life of dairy products, in a process called biopreservation. The research in this area has been leveraged by consumers demand for naturally preserved foods. Dairy products are natural niches for Lactococcus lactis strains, and these bacteria have been associated with food production and preservation since ancient times. As a dominant species in dairy ecosystems, L. lactis strains are very interesting because they are not likely to require regulatory approval for practical application as bioprotective cultures.
Modulations of bovine hepatic microsomal metabolism of benzimidazoles by secondary plant metabolites
Authors: Karlik Wojciech , Chłopecka Magdalena , Bamburowicz‐Klimkowska Magdalena , Mendel Marta
Published: November 2018

The study was aimed to estimate the effect of plant secondary metabolites present in ruminants diet and phytogenic feed additives on liver microsomal metabolism of albendazole and fenbendazole. The selected phytocompounds comprised of flavonoids (apigenin, quercetin) and saponins (hederagenin, medicagenic acid). The experiments were performed on liver microsomal fraction obtained from routinely slaughtered cows. The intensity of albendazole and fenbendazole metabolism in the presence of flavonoids and saponins was analyzed in equimolar concentration (100 μM). The obtained results revealed that both flavonoids and saponins intensify the metabolism of albendazole and fenbendazole in bovine microsomes. In the case of albendazole, apigenin and quercetin doubled the amount of degraded drug and the amount of produced albendazole sulfoxide. Additionally, both flavonoids increased the amount of produced albendazole sulfone. Saponins, hederagenin, and medicagenic acid intensified the degradation of albendazole (1.8‐fold) and the production of albendazole sulfoxide (twofold). Medicagenic acid inhibited the production of albendazole sulfone. In the case of fenbendazole, the degradation of the drug and the production of oxfendazole were increased four and five times in the presence of saponins and flavonoids, respectively. The enhancement of benzimidazoles’ metabolism caused by the studied plant metabolites could change pharmacokinetics and the efficacy of benzimidazoles’ treatment in cattle.
Age‐related changes in interstitial fibrosis and germ cell degeneration of the canine testis
Authors: Bhanmeechao Cholayuth , Srisuwatanasagul Sayamon , Ponglowhapan Suppawiwat
Published: November 2018

Contents

Fifty‐five healthy medium‐sized dogs were divided into four groups; young (1–3 years old, n = 14), adult (>3 to 6 years old, n = 12), old (>6 to 9 years old, n = 14) and senile (>9 years old, n = 15). After routine orchiectomy, testes were collected, and the degree of white streak areas on cut surfaces was subjectively assessed. Later, testicular tissue sections were stained with haematoxylin and eosin and Masson's trichrome for evaluation of germ cell degeneration and the proportion of interstitial connective tissue, respectively. Semiquantitative severity scoring of germ cell degeneration and quantitative analysis of spermatogenic cells for spermatic index (SI) and Sertoli cell index (SEI) was performed. The score of white streak on cut surface area of the testes increased with age, being higher (p < 0.05) in senile dogs than other age groups; no difference was found between adult and old dogs. The proportion of testicular interstitial fibrosis was highest (p < 0.05) in senile dogs. Positive correlations between age and white streak area (rho = 0.77, p < 0.01) as well as age and interstitial fibrosis (rho = 0.63, p < 0.01) were observed. The severity of germ cell degeneration gradually increased with age and differed among age groups (p < 0.05). Age positively correlated with atrophy of seminiferous tubules (rho = 0.93, p < 0.01). The SI was lower (p < 0.05) in senile dogs compared to other age groups, and SI was not different among young, adult and old dogs. Conversely, SEI was significantly higher in senile dogs compared to young, adult and old dogs. A negative correlation between age and SI (rho = −0.69) and a positive correlation between age and SEI (rho = 0.68) were significant (p < 0.01). In conclusion, influence of age on testicular interstitial fibrosis and germ cell degeneration/depletion were pronounced in dogs over 9 years old.
Manipulation of the oestrous cycle of the bitch—what works… for now
Authors: Maenhoudt Cindy , Santos Natalia R. , Fontbonne Alain
Published: November 2018

Contents

Manipulation of the oestrous cycle of the bitch is a common request of pet owners for different reasons. On one side, clients may be interested in temporally preventing oestrus until the bitch has finished the performance career, or to manage the kennel in the presence of a stud dog and to avoid undesirable breeding. Additionally, clients with no interest to use their animal for breeding, may, for ethical reasons, prefer to avoid elective surgery such as ovariectomy, to control reproduction. On the other side, clients may want to induce oestrus to better control the time of birth, to use a male with limited availability during a specific time, or to reduce the duration of the interoestrous interval in bitches with a long oestrous cycle (>8 months). Both these options for oestrous manipulation are based on hormonal treatments. For oestrous prevention, synthetic progesterone has been used since the 1960s. Induction of oestrus has been established with reliable results using dopamine agonists in the late 1980s and more recently using GnRHagonists. This review is focusing on the current and recently available treatments to manipulate the oestrous cycle in the bitch.
Treating hepatitis C virus in dialysis patients: How, when, and why?
Authors: Pagan Javier , Ladino Marco , Roth David
Published: November 2018

The identification of hepatitis C virus (HCV) occurred in 1989, and soon thereafter, it was recognized that there was a higher prevalence of anti‐HCV seropositivity in patients with end‐stage renal disease (ESRD) when compared to the general population. Multiple extrahepatic manifestations have been associated with HCV infection in patients with ESRD; these include an increased prevalence and risk of cardiovascular complications, insulin resistance, diabetes mellitus, and lymphoproliferative disorders. Infection with HCV has also been associated with an increased relative risk of mortality in the ESRD patient when contrasted to those patients without infection. The availability of second‐generation direct‐acting antiviral agents has revolutionized the treatment of HCV in both the general population as well as those patients with advanced chronic kidney disease and receiving dialysis. These new treatment protocols are very well tolerated with limited side effects and manageable drug‐drug interactions while achieving remarkable sustained viral response rates. It is important that nephrologists become familiar with the differing strategies available for HCV‐infected ESRD patients so that the appropriate decision of when and who to treat can be made for each patient.
Measuring Away the Importance of Institutions: The Case of Seigneurial Tenure and Agricultural Output in Canada East, 1851*
Authors: Geloso Vincent
Published: November 2018

This article argues that the 1851 census of Canada East (the modern‐day province of Quebec) requires a set of important corrections. Using corrections based on ethnic origin composition, I demonstrate how significantly wheat and oat yields were underestimated in Canada East. More importantly, I argue that the measurement errors are not randomly distributed and that they are biased against attempts to test the role of institutions. I show how the new method of correcting the data change our interpretation of agricultural efficiency in Lower Canada in the mid‐19th century. While this correction may seem minor, it shows that in the past, the data took a form that was biased against numerous hypotheses concerning land tenure institutions.
Risky Business: Institutional Logics and Risk Taking at Large U.S. Commercial Banks*
Authors: LaBriola Joe
Published: November 2018

Objective

This article aims to answer whether increased securitization and/or increased shareholder value pressures at commercial banks have led to higher levels of risk.

Methods

Using data on large U.S. commercial banks from several sources, I estimate linear partial‐adjustment models to predict the effects of securitization, as well as CEO incentives to increase shareholder value, on leverage.

Results

These models provide evidence that increases in the relative size of trading securities at a commercial bank are significantly associated with increases in leverage. Meanwhile, the relative size of total securities and CEO incentives to increase shareholder value do not appear to affect leverage.

Conclusion

These findings suggest that limiting commercial bank speculation in securities markets may reduce the likelihood that commercial banks face large losses or become insolvent in financial downturns.
How to…analyse qualitative data in different ways
Authors: Bennett Dierdre , Barrett Aileen , Helmich Esther
Published: November 2018

In this paper, the fifth in a series on qualitative research in medical education, we discuss approaches to analysing qualitative data. We focus primarily on analysing transcribed interview and focus group data. We also touch on the analysis of visual data, a potentially fruitful alternative approach.
Qualitative topological relations between interval type‐2 fuzzy spatial objects
Authors: Guo Jifa , Shao Xiaodong , Mo Xunqiang
Published: November 2018

The topological relations between fuzzy objects are crucial in geographical spatial analysis. A qualitative topological relationship analysis method for interval type‐2 fuzzy spatial objects (IT2 FSOs) is proposed in this article. Similarities between the interval type‐2 fuzzy topological relation matrices and the corresponding crisp topological relation matrices are calculated using Jaccard's similarity measure and sorted to identify the two major relations. Next, the proximity degrees and quantifiers that correspond to these two major relations can be determined. Thus, two methods can be used to describe the relation between two IT2 FSOs; the method proposed in this article conforms to human cognitive habits and meets the requirements of a variety of applications in geographical information systems (GIS). Users can select different boundary definitions, intersection matrix types, and calculation functions for each cell in the intersection matrix, as well as different description methods according to the requirements of different GIS applications.
Examination of Changes in Certain Biochemical Parameters Before and After Acute Training in Kick Boxers
Authors: Karadağ Mustafa , Gür Ercan , Kargün Kürşat , Savucu Yüksel , Eskiyecek Gülbin
Published: November 2018

Kickbox is one of the modern martial sports. The psychophysiological demands of a kickbox competition require that athletes achieve high thresholds in various aspects of physical fitness.The aim of this study is to analyze and evaluate the physiological properties of kickbox athletes and the activity profile properly in order to put forward proposals for training and new scientific research fields. The blood samples, which were taken before and after the maximal training applied to athletes according to the period, were studied. A total of 50 athletes, including 39 male and 11 female amateurs, were included in the study, with an average age of 20.08±6.33 years. All participants were informed about the study and necessary approvals. There was a significant difference between males and females in terms of BMI (Body Mass Index). It was observed that the GSH values of the athletes increased before and after training in both males and females. On the other hand, IL-1B (interleukin) only increased in males (p<0.05). The information obtained shows that the analyses of the before and after training male kickboxers at the amateur level are significantly more different than that of women. Since GSH is an effective tripeptide of antioxidants involved in the detoxification of harmful compounds, its synthesis is very important for metabolism. It can be said that GSH (glutathione) level may increase with normal exercise in daily life and training in athletes. Furthermore, the athletes should be analyzed metabolically well in response to the stress that may be caused by heavy exercise, and the exercise for improving performance should be achieved by detecting biochemical changes.
Two-Phase Pipe Quenching Correlations for Liquid Nitrogen and Liquid Hydrogen
Authors: Darr S. R. , Hartwig J. W. , Dong J. , Wang H. , Majumdar A. K. , LeClair A. C. , Chung J. N.
Published: November 2018

Recently, two-phase cryogenic flow boiling data in liquid nitrogen (LN2) and liquid hydrogen (LH2) were compared to the most popular two-phase correlations, as well as correlations used in two of the most widely used commercially available thermal/fluid design codes in Hartwig et al. (2016, “Assessment of Existing Two Phase Heat Transfer Coefficient and Critical Heat Flux on Cryogenic Flow Boiling Quenching Experiments,” Int. J. Heat Mass Transfer, 93, pp. 441–463). Results uncovered that the correlations performed poorly, with predictions significantly higher than the data. Disparity is primarily due to the fact that most two-phase correlations are based on room temperature fluids, and for the heating configuration, not the quenching configuration. The penalty for such poor predictive tools is higher margin, safety factor, and cost. Before control algorithms for cryogenic transfer systems can be implemented, it is first required to develop a set of low-error, fundamental two-phase heat transfer correlations that match available cryogenic data. This paper presents the background for developing a new set of quenching/chilldown correlations for cryogenic pipe flow on thin, shorter lines, including the results of an exhaustive literature review of 61 sources. New correlations are presented which are based on the consolidated database of 79,915 quenching points for a 1.27 cm diameter line, covering a wide range of inlet subcooling, mass flux, pressure, equilibrium quality, flow direction, and even gravity level. Functional forms are presented for LN2 and LH2 chilldown correlations, including film, transition, and nucleate boiling, critical heat flux, and the Leidenfrost point.
Sustainable Manufacturing With Cyber-Physical Discrete Manufacturing Networks: Overview and Modeling Framework
Authors: Garcia Daniel J. , Mozaffar Mojtaba , Ren Huaqing , Correa Jorge E. , Ehmann Kornel , Cao Jian , You Fengqi
Published: November 2018

Cyber-physical systems (CPS) enable unprecedented communication between product designers and manufacturers. Effective use of these technologies both enables and requires a new paradigm of methods and models to identify the most profitable and environmentally friendly production plans for a manufacturing network. The operating system for cyber-physical manufacturing (OSCM) and the paired network operations administration and monitoring (NOAM) software are introduced. These technologies guide our development of a mixed integer bilevel programming (BP) model that models the hierarchy between designers and manufacturers as a Stackelberg game while considering multiple objectives for each of them. Designers select and pay manufacturers, while manufacturers decide how to execute the order with the payment provided by the designer. To solve the model, a tailored solution method combining a decomposition-based approach with approximation of the lower level Pareto-optimal solution set is proposed. The model is applied to a case study based on a network of manufacturers in Wisconsin and Illinois. With the proposed model, designers and manufacturers alike can take full advantage of CPS to increase profits and decrease environmental impacts.
Understanding the Role of Additive Manufacturing Knowledge in Stimulating Design Innovation for Novice Designers
Authors: Yang Sheng , Page Thomas , Zhao Yaoyao Fiona
Published: November 2018

Additive manufacturing (AM) is recognized as a disruptive technology that offers significant potentials for innovative design. Prior experimental studies have revealed that novice designers provided with AM knowledge (AMK) resources can generate a higher quantity and quality of solutions in contrast with control groups. However, these studies have adopted coarse-grain evaluation metrics that fall short in correlating AMK with radical or architectural innovation. This deficiency directly affects the capturing, modeling, and delivering AMK so that novel opportunities may be more efficiently utilized in ideation stage. To refine the understanding of AMK's role in stimulating design innovation, an experimental study is conducted with two design projects: (a) a mixer design project, and (b) a hairdryer redesign project. The former of which aims to discover whether AMK inspiration increases the quantity and novelty of working principles (WP) (i.e., radical innovation), while the latter examines the influence of AMK on layout and feature novelty (i.e., architectural innovation). The experimental study indicates that AMK does have a positive influence on architectural innovation while the effects on radical innovation are very limited if the example illustrating the AMK is functionally irrelevant to the design problem. Two strategies are proposed to aid the ideation process in maximizing the possibility of identifying AM potentials to facilitate radical innovation. The limitations of this study and future research plans are discussed.
Front/Rear Axle Torque Vectoring Control for Electric Vehicles
Authors: Ruiz Diez David , Velenis Efstathios , Tavernini Davide , Smith Edward N. , Siampis Efstathios , Soltani Amir
Published: November 2018

Vehicles equipped with multiple electric machines allow variable distribution of propulsive and regenerative braking torques between axles or even individual wheels of the car. Left/right torque vectoring (i.e., a torque shift between wheels of the same axle) has been treated extensively in the literature; however, fewer studies focus on the torque shift between the front and rear axles, namely, front/rear torque vectoring, a drivetrain topology more suitable for mass production since it reduces complexity and cost. In this paper, we propose an online control strategy that can enhance vehicle agility and “fun-to-drive” for such a topology or, if necessary, mitigate oversteer during sublimit handling conditions. It includes a front/rear torque control allocation (CA) strategy that is formulated in terms of physical quantities that are directly connected to the vehicle dynamic behavior such as torques and forces, instead of nonphysical control signals. Hence, it is possible to easily incorporate the limitations of the electric machines and tires into the computation of the control action. Aside from the online implementation, this publication includes an offline study to assess the effectiveness of the proposed CA strategy, which illustrates the theoretical capability of affecting yaw moment that the front/rear torque vectoring strategy has for a given set of vehicle and road conditions and considering physical limitations of the tires and actuators. The development of the complete strategy is presented together with the results from hardware-in-the-loop (HiL) simulations, using a high fidelity vehicle model and covering various use cases.
Streamlining the Power Generation Profile of Concentrating Solar Power Plants
Authors: Abutayeh Mohammad , Jeong Kwangkook , Alazzam Anas , El-Khasawneh Bashar
Published: November 2018

A scheme to streamline the electric power generation profile of concentrating solar power (CSP) plants of the parabolic trough collector (PTC) type is suggested. The scheme seeks to even out heat transfer rates from the solar field (SF) to the power block (PB) by splitting the typical heat transfer fluid (HTF) loop into two loops using an extra vessel and an extra pump. In the first loop, cold HTF is pumped by the cold pump from the cold vessel to the SF to collect heat before accumulating in the newly introduced hot vessel. In the second loop, hot HTF is pumped by the hot pump from the hot vessel to a heat exchanger train (HXT) to supply the PB with its heat load before accumulating in the cold vessel. The new scheme moderately decouples heat supply from heat sink allowing for more control of heat delivery rates thereby evening out power generation.
Synergizing Product Design Information and Unit Manufacturing Process Analysis to Support Sustainable Engineering Education
Authors: Raoufi Kamyar , Manoharan Sriram , Haapala Karl R.
Published: November 2018

Promoting excellence in sustainable manufacturing has emerged as a strategic mission in academia and industry. In particular, universities must prepare the next generation of engineers to contribute to the task of sustaining and improving manufacturing by providing appropriate types of sustainability education and training. However, engineering curricula are challenged in delivering educational training for assessing technical solutions from the three domains that define sustainability: economic, environmental, and social. In the research presented here, an educational framework is developed with an aim to improve student understanding of sustainable product design (PD) and manufacturing. The framework is founded on the analyze, design, develop, implement, and evaluate (ADDIE) model for instructional design. The developed framework is demonstrated using an example of a sustainable PD activity. This instructional design case study illustrates how engineering students would be able to investigate the impacts of raw materials, unit manufacturing processes, manufacturing locations, and design changes on product sustainability performance by integrating PD information and manufacturing analysis methods during the PD phase.
Diagnosis Method for Valve-Controlled Hydraulic Cylinder Leakage Based on Subspace Identification
Authors: Guo Junxia , Tao Jianfeng , Li Lin , Liu Chengliang
Published: November 2018

This paper proposes a fault diagnosis method based on subspace identification for the leakage fault detection of valve-controlled hydraulic cylinders. Firstly, the state-space model for the system is established, in which the external force on the piston of the hydraulic cylinder is selected as input signal, and the pressure of the two chambers, displacement and velocity of piston rod are chosen as state variables. Then, the estimation value of specific elements of the system matrix can be obtained in terms of the subspace identification theory. On this basis, the existence, type and level of the leakage fault are determined. Finally, the numerical simulation is conducted through MATLAB-Simulink to verify the proposed method. The results demonstrate that the proposed method is effective and has high accuracy.
Investigating Electrostatic Flow Charging Using a Small Scale Test Bench
Authors: Weishaar Philipp C. , Görres Alexander , Murrenhoff Hubertus , Schmitz Katharina
Published: November 2018

Common examples for electrostatic discharges can be encountered in everyday life. When approaching a grounded surface after walking on insulating flooring material or while riding an escalator one might experience an electrostatic discharge first hand. These discharges generally do not pose a problem but when translated to various fields of engineering, such as in hydraulics, discharges can be the root cause for system failures. The pioneering fields of engineering for electrostatic charging in systems are petro-chemistry and electrical engineering. Researchers in both fields attempted to formulate models to calculate the electrostatic charging a priori. These models provide some indication regarding the magnitude of charge but are currently not suited for the application in hydraulic systems. This is due to the lack of necessary fluid and material parameters for the application of either one of the models. [1, 2]

Previous work in the pioneering fields focused on fluids and materials typical for their respective applications. This paper seeks to take the first step to remedy this situation by developing and commissioning a test bench for investigating a wide variety of hydraulic fluid-material combinations. The fluids pending investigation range from a typical hydraulic fluid based on a group I base oil to a pure polyalphaolefine of group IV. Common materials for hydraulic systems are investigated with a small scale test bench as well, such as steel and brass common to hydraulic applications as well as plastics and rubbers. In order to conduct these investigations a Searle viscometer is presented in this paper. In a Searle viscometer the cylinder is rotating while the cup or pipe remains stationary.

Initially this paper gives the necessity for a small scale test bench using experimental results of an existing large scale test rig. Subsequently, the design of a small scale test bench, the Searle viscometer, will be presented along with a method for measuring the charge density. The small scale test bench is based on the work of Washabaugh and is able to generate the necessary information required for using the chemical reaction-based model [3, 4]. The main feature of the chemical reaction based model is the consideration for different material and fluid influences, beyond the scope of viscosity and system geometry.
Addressing Valves With Pressure Ripple
Authors: Foss Ryan J. , Li Mengtang , Barth Eric J. , Stelson Kim A. , Van de Ven James D.
Published: November 2018

Pressure ripple can be purposely used to transmit information within a hydraulic system. For example, introducing ripple at specific frequencies into a fluid line can activate a valve, eliminating electrical wires. A key element of this system is the hydraulic resonator that activates the valve when a specific frequency pressure ripple is present in the line. This paper presents a linear and nonlinear model of the hydraulic resonator with experimental validation. The hydraulic resonator consists of an inertance tube, a series capacitor, made up of a deforming elastic membrane, and an orifice. For system validation, displacement of a valve, the capacitor, and system pressure are measured. The model was effective at predicting the natural frequency of the system and the narrowness of the resonant peak. Different effects were also shown experimentally by changing the fluid’s viscosity and system parameters.
Symmetric Single Rod Cylinders With Variable Piston Area? A Comprehensive Approach to the Right Solution
Authors: Kolks Giacomo , Weber Jürgen
Published: November 2018

In contrast to rotational hydraulic displacement units, such as pumps or motors, conventional hydraulic cylinder actuators do not allow a continuous variation of their displacement quantity: the piston area is regarded constant. In order to adapt to varying load and velocity requirements in a load cycle under torque restrictions of the driving motor, cylinder drives often implement pumps with variable displacement.

In this paper, cylinders with discretely variable effective piston area by means of variable circuitry of multi-chamber cylinders are discussed. Hydraulic symmetry or constant asymmetry of the hydraulic cylinder are traits of the cylinder that are required to fit the cylinder to pump structures for closed-circuit displacement control, as given in electro-hydrostatic compact drives (ECD). A methodology to generate all possible solutions of variable area cylinders under the constraint of ECD requirements is proposed.

A comprehensive description of the solution space is given, based on combinatorics and solution of equation systems. The methodology dealing with abstract cylinder areas is backed up by a general approach to describe the mechanical cylinder design space to combine multiple cylinder areas in one structural unit. Examples for design of three and four area cylinders are given and results are discussed. The paper concludes with the development of a demonstrator design to allow experimental validation in a subsequent step.
Determination of the Dynamic Characteristics of a Hydraulic Reservoir for its Air Release Efficiency Using Multiphase CFD Model
Authors: Mostafavi Rahelehsadat , Tiffin Dominic , Schmitz Katharina
Published: November 2018

Undissolved air in oil causes various problems for hydraulic systems and strongly decreases the efficiency of the system. In this respect, the hydraulic reservoir as the only component that performs the function of releasing the accumulated air from the system is relevant. In recent years, the air release efficiency in hydraulic reservoirs has been studied both experimentally and in simulation. However, in none of the according studies dynamically changing flow conditions have been considered.

In this paper, the air release behaviour of a hydraulic reservoir is investigated through simulation, considering the dynamics of the system. The developed multiphase CFD model utilizes the open-source CFD tool, OpenFOAM®, based on a Lagrangian Particle Tracking (LPT) within an Eulerian phase. The simulations have been conducted varying the key variables such as oil flow rate and air load at the inlet of the reservoir and yield the air content at the outlet.
A Survey of Industrial Internet of Things in the Field of Fluid Power: Basic Concept and Requirements for Plug-and-Produce
Authors: Alt Raphael , Malzahn Justus , Murrenhoff Hubertus , Schmitz Katharina
Published: November 2018

Driving aspects in the developments of the Industrial Internet of Things (IIoT) are based on markets demanding a highly flexible production on the one hand and, on the other hand, by the production industry looking for new business models. This is enabled by interconnecting intelligent devices and aggregating and analyzing huge amounts of data. In the section of field devices, targeted new developments are dealing with intelligent systems which support users in each stage of the product life cycle. During installation and commissioning of a new machine, the concept of Plug-and-Produce has been created in the production industry. It is relating to the analogy of Plug-and-Play in the field of information technology which makes it possible to recognize and use devices without additional effort across several platforms. Industrial production systems differ in some aspects from Plug-and-Play computer devices that these methods are not applicable without adjustments and more advanced considerations.

Solutions to support the commissioning process are scope of this contribution and analyzed theoretically by the example of the integration of an electro-hydraulic actuator.

Two results are highlighted in this contribution. Different IIoT related concepts and technologies (i.e. OPC-UA, Cyber-physical systems, semantics) are presented and merged to realize Plug-and-Produce as an holistic business process. Furthermore, the draft combines the domain of fluid power with the abstract and generalized concepts and models and gives an understanding of future requirements for fluid power field devices in the context of IIoT.
Predictive Robust Control Based on Higher-Order Sliding Mode for Passive Heave Compensator With Hydraulic Transformer
Authors: Yu Huan , Wei Jianhua , Fang Jinhui , Sun Ge , Zhang Hangjun
Published: November 2018

Passive heave compensation (PHC) system is widely applied in offshore equipment because of its superiority in energy conserving and reliability. However, it has poor adaptability to changing sea conditions and the compensation accuracy is low. Hydraulic transformer (HT), working as a pressure-flow control element, can potentially solve the problems mentioned above. In this paper, an HT based PHC (HTPHC) system is proposed for the first time, and a compensation algorithm based on higher-order sliding mode (HOSM) together with a prediction algorithm for the heave motion of the vessel is derived to get good compensation effect using the new PHC system. The prediction algorithm is proved to be effective according to the measured data of sea trials, and reduces the difficulty of designing and parameter tuning process compared with the existing ones. The effectiveness of the proposed control algorithm is evaluated with simulation, moreover, the effectiveness can still be maintained under changing sea conditions which is also verified by simulation.
A Novel Piezoelectric Double-Flapper Servovalve Pilot Stage: Operating Principle and Performance Prediction
Authors: Tamburrano Paolo , Amirante Riccardo , Distaso Elia , Plummer Andrew R.
Published: November 2018

This paper proposes a novel architecture for the pilot stage of electro-hydraulic two-stage servovalves that does not need a quiescent flow and a torque motor as well as a flexure tube to operate. The architecture consists of two small piezoelectric valves, coupled with two fixed orifices, which allow variation of the differential pressure at the main stage spool extremities in order to move it with high response speed and accuracy. Each piezoelectric valve is actuated by a piezoelectric ring bender, which exhibits much greater displacement than a stack actuator of the same mass, and greater force than a rectangular bender. The concept is intended to reduce the influence of piezoelectric hysteresis. In order to assess the validity of the proposed configuration and its controller in terms of spool positioning accuracy and dynamic response, detailed simulations are performed by using the software Simscape Fluids. At 50% amplitude the −90° bandwidth is about 150Hz.
Exploiting Valve Timing for Pneumatic Energy Savings
Authors: Padovani Damiano , Barth Eric J.
Published: November 2018

This research paper aims at addressing solutions that reduce air consumption in generic pneumatic systems used for pick-and-place operations. The investigation considers different system architectures both with a single control valve and two control valves arranged according to an independent metering configuration. Suitable control strategies are then proposed exploiting multiple timings to shut off the non-proportional switching valve(s). The resulting scenarios are experimentally evaluated on a dedicated test-bed. The main conclusion is that reduction of air consumption up to 73% is possible in comparison to the state-of-the-art layout for the reference application. Numerical simulations obtained by means of specific dynamic models suggest these air savings are consistent for actuators with different strokes.
Four Quadrant Hybrid Control Oriented Dynamical System Model of Digital Displacement® Units
Authors: Pedersen Niels H. , Johansen Per , Andersen Torben O.
Published: November 2018

Proper feedback control of dynamical systems requires models that enables stability analysis, from where control laws may be established. Development of control oriented models for digital displacement (DD) fluid power units is complicated by the non-smooth behavior, which is considered the core reason for the greatly simplified state of the art control strategies for these machines. The DD unit comprises numerous pressure chambers in a modular construction, such that the power throughput is determined by the sequence of activated pressure chambers. The dynamics of each pressure chamber is governed by non-linear differential equations, while the binary input (active or inactive) is updated discretely as function of the shaft angle. Simple dynamical approximations based on continuous or discrete system theory is often inaccurate and is not applicable for such system when it is to operate in all four quadrants. Therefore, a method of applying hybrid dynamical system theory, comprising both continuous and discrete elements is proposed in this paper. The paper presents a physical oriented hybrid model accurately describing the machine dynamics. Since development of stabilizing control laws for hybrid dynamical systems is a complicated task, a simpler hybrid model only including the fundamental machine characteristics is beneficial. Therefore, a discussion and several proposals are made on how a simpler DD hybrid model may be established and used for feedback control development.
Hydraulic-Mechanic Damper Concept for Thruster Ice Impact Load Reduction
Authors: Siivonen Lauri , Tammisto Jyrki , Huhtala Kalevi , Tiainen Olli
Published: November 2018

A novel hydraulic-mechanic damper was designed and dimensioned for damping of ice loads of a steerable thruster. The system consists of inertia masses and four hydraulic cylinders acting as spring and damping elements. The system is energy self-sufficient and fail-safe. Simulation model is used to study the damping potential and applicability of the system. Comparison between system with and without dampers showed clear advantages and potential for effecting the life time of the thruster gearbox.
Modelling of the Lateral Lubricating Interfaces in External Gear Machines Considering the Effects of Cavitation
Authors: Thiagarajan Divya , Vacca Andrea
Published: November 2018

This work presents an approach for evaluating the cavitating conditions encountered in the lateral lubricating interfaces which exist between floating lateral bushings and gears in external gear machines (EGMs). Previous work in the authors’ research team had resulted in the development of a full fluid-structure-interaction (FSI)-EHD lubricating model for the lateral lubricating gaps, which was also validated against experiments. However, such a model uses a very simplified and approximate approach to consider aeration or cavitating conditions in the lubricating gap, where the pressures are simply saturated to a constant minimum value during their solution whenever they cross a minimum threshold. This subsequently results in numerically unstable predictions of pressure when substantial cavitating regions are encountered while also violating mass conservation laws.

To overcome these issues, this paper presents a stable mass conserving cavitation algorithm by implementing the universal Reynolds equation in the existing FSI-EHD model which is applicable for both full film and cavitating conditions and has been found to be applicable in several other tribological interfaces. Such a method offers to predict the onset and shape of the cavitating regions without the need for considering complex bubble dynamics. After outlining the formulation and implementation of the new cavitation algorithm, this paper also presents simulations of a commercially available EGM, where using this cavitation algorithm was found to predict realistic pressure distributions in the lubricating interface while also maintaining the stability of such a complex lubricating gap model for EGMs.
Development of Visualized Water Hydraulic Experiment System for Studying the Bubble Flow Pattern Inside Valve
Authors: Wang Haihang , Xu He , Zhao Zitong , Pooneeth Vishwanath , Jiao Liye
Published: November 2018

To study the flow pattern mechanism of cavitation and erosion in water hydraulic valves, a visualized water hydraulics experiment for testing the bubble flow was designed and conducted in this paper. An ergonomic design method was adopted to ensure with the characteristics of the visualized experiment platform of being modular, movable, networked, adopting a virtual three-dimensional vision and safety, respectively, were adhered. An experimental video acquisition subsystem with an optimized arrangement of 5 plane mirrors was presented to observe and analyze the bubble flow pattern in a transparent hydraulic valve. An algorithm was developed to extract the 2-D bubble features and reconstruct the 3-D bubble flow pattern. The 2-D and 3-D calculated results were analyzed, which effectively reconstructed the bubble flow. During the 2-D and 3-D results analysis for a selected period of time, the visualized water hydraulics experiment system in this paper met the expected performance requirements.
High-Fidelity Model of Electro-Hydraulic Actuators for Primary Flight Control Systems
Authors: De Martin Andrea , Dellacasa Andrea , Jacazio Giovanni , Sorli Massimo
Published: November 2018

Hydraulic actuators are the de facto standard for primary flight control systems, since they provide low jamming probability and intrinsic damping capabilities. Electro-Hydraulic Actuators theoretically provide a number of advantages over the traditional hydraulic systems, such as the decrease in the overall power consumption, easier installation and reduced weight of the flight control system, but are so far mostly used as back-up solutions in civil applications. Flight control actuators can face an extremely wide range of operational scenarios depending on the aircraft route, weather condition, pilot behavior and components health. The use of high-fidelity models is instrumental in the design of both actuators and control laws and can enhance the definition of a Prognostics and Health Monitoring system, given its capability to simulate a huge number of possible in-flight situations. In this paper, we provide the mathematical definition of a novel high-fidelity model for primary flight control system, discuss its implementation and results in nominal and off-nominal conditions.