bluuebunny/crossref_metadata_2025_split huggingface dataset:
Age‐dependent impact of CaV3.2 T‐type calcium channel deletion on myogenic tone and flow‐mediated vasodilatation in small arteries
Authors: Mikkelsen Miriam F. , Björling Karl , Jensen Lars Jørn 
Published: January 2016

Key points
Blood pressure and flow exert mechanical forces on the walls of small arteries, which are detected by the endothelial and smooth muscle cells, and lead to regulation of the diameter (basal tone) of an artery.
CaV3.2 T‐type calcium channels are expressed in the wall of small arteries, although their function remains poorly understood because of the low specificity of T‐type blockers.
We used mice deficient in CaV3.2 channels to study their role in pressure‐ and flow‐dependent tone regulation and the possible impact of ageing on this role.
In young mice, CaV3.2 channels oppose pressure‐induced vasoconstriction and participate in endothelium‐dependent, flow‐mediated dilatation. These effects were not seen in mature adult mice.
The results of the present study demonstrate an age‐dependent impact of CaV3.2 T‐type calcium channel deletion in rodents and suggest that the loss of CaV3.2 channel function leads to more constricted arteries, which is a risk factor for cardiovascular disease.
AbstractThe myogenic response and flow‐mediated vasodilatation are important regulators of local blood perfusion and total peripheral resistance, and are known to entail a calcium influx into vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), respectively. CaV3.2 T‐type calcium channels are expressed in both VSMCs and ECs of small arteries. The T‐type channels are important drug targets but, as a result of the lack of specific antagonists, our understanding of the role of CaV3.2 channels in vasomotor tone at various ages is scarce. We evaluated the myogenic response, flow‐mediated vasodilatation, structural remodelling and mRNA + protein expression in small mesenteric arteries from CaV3.2 knockout (CaV3.2KO) vs. wild‐type mice at a young vs. mature adult age. In young mice only, deletion of CaV3.2 led to an enhanced myogenic response and a ∼50% reduction of flow‐mediated vasodilatation. Ni2+ had both CaV3.2‐dependent and independent effects. No changes in mRNA expression of several important K+ and Ca2+ channel genes were induced by CaV3.2KO However, the expression of the other T‐type channel isoform (CaV3.1) was reduced at the mRNA and protein level in mature adult compared to young wild‐type arteries. The results of the present study demonstrate the important roles of the CaV3.2 T‐type calcium channels in myogenic tone and flow‐mediated vasodilatation that disappear with ageing. Because increased arterial tone is a risk factor for cardiovascular disease, we conclude that CaV3.2 channels, by modulating pressure‐ and flow‐mediated vasomotor responses to prevent excess arterial tone, protect against cardiovascular disease.
Dynamical Model Research on Energy-Conversion Process of Giant Magnetstrictive Materials-Based Electrohydrostatic Actuator
Authors: Zhu Yuchuan , Yang Xulei 
Published: January 2016

A giant Magnetstrictive materials-based Electro-hydrostatic Actuator (MEHA) is shown by presenting its structure configuration and working principle, which include a Giant Material Actuator (GMA), pump, two one-way check valves, a cylinder and utilize fluid rectification via one-way check valves to amplify the small, high-frequency vibrations of GMA into large motions of a hydraulic cylinder.
The established dynamic model of a MEHA involves five submodels from the viewpoint of energy conversion: the dynamic model of the power amplifier; the dynamic magnetization model that describes the relationship between the exciting current and the magnetization of the Giant Magnetostrictive Material (GMM) rod; the magnetoelastic model describing the relationship between the magnetostrictive strain and the magnetization of GMM rod; the kinetic model of the GMA describing the relationship between the GMA displacement (piston displacement of pump) and the magnetostrictive strain; the cylinder motion model.
By the simulation to the above model, dynamic characteristics of MEHA are clearly exhibited by the dynamic response curves, which show a good agreement with the experimental data and gives a scientific explanation about the test results.
A Survey on Negative Control Architectures for Hydraulic Excavators
Authors: Gessi Silvia , Martelli Massimo , Tonini Emanuele 
Published: January 2016

The present survey is one step of a complex research activity, directed toward the conception of innovative solutions for hydraulic directional control valves for excavators of the 20-ton category.
In the world scene, as far as the hydraulic circuit present in this type of machines is concerned, a wide diffusion of the Negative Control and Positive Control architectures is observed; in literature it is also possible to find “hybrid” configurations that try to optimize system operation by taking advantage of the peculiarities of the above mentioned architectures.
Although the mechanical structure of the excavators is practically standardized among the different manufacturers, interesting solutions and configurations are adopted in the implementation of the directional control valve.
The present work aims to analyze and describe the common features observed in some of the commercial devices for the Negative Control architecture, starting from their basic structure (i.e. layout and number of sections), to get to the study of internal regenerations and external confluences (or junctions). In order to understand, in detail, the characteristics of some constructive choices (common and not, between the manufacturers), a full excavator model was implemented in the AMESim simulation environment, that includes a complex directional control valve, actuators and a 3D mechanism with 9 degrees of freedom representing the excavator’s kinematics.
By means of the simulation model, using the relevant JCMAS standards as a guideline for representative working cycles, a qualitative analysis of system operation is carried out, with a particular focus on multiple actuations (complex movements).
Energy Cost of Avoiding Pressure Oscillations in a Discrete Fluid Power Force System
Authors: Hansen Anders Hedegaard , Pedersen Henrik C. 
Published: January 2016

In secondary valve controlled discrete fluid power force systems the valve opening trajectory greatly influences the pressure dynamics in the actuator chambers. For discrete fluid power systems featuring hoses of significant length pressure oscillations due to fast valve switching is well-known.
This paper builds upon theoretical findings on how shaping of the valve opening may reduce the cylinder pressure oscillations. The current paper extents the work by implementing the valve opening characteristics reducing the pressure oscillations on a full scale power take-off test-bench for wave energy converters. Further the energy losses introduced during the shifting period is investigated and compared for two valve opening algorithms. The investigation of the energy loss is utilised to quantify the importance of a fast valve switching and the energy cost of reducing pressure oscillations.
The paper will present measurements comparing pressure dynamics for two valve opening algorithms. In addition the paper will give a theoretical investigation of the energy loss during valve shifting and finally measurements of average power output from the power take-off system in various sea states are compared for the three pressure shifting times.
Investigation of Load Reduction Possibilities in Wind Turbines Using a Fluid Power Pitch System
Authors: Pedersen Henrik C. , Andersen Torben O. , Liniger Jesper 
Published: January 2016

The pitch system is a central part of modern wind turbines and good pitch control is essential for proper operation of the wind turbine. However, often when considering the pitch control, the pitch system dynamics is approximated by a simplified low order model, which may be acceptable for electrical pitch systems and turbine control purposes, but which does not capture the potential damping possibilities that may arise by actively using the fluid power systems to reduce the loads on the wind turbine structure. The focus of the current paper is therefore on the load reduction possibilities arising from applying an active damping filter in the fluid power systems to damp structural loads on the wind turbine, while maintaining the power production.
Utilising the 5MW NREL reference wind turbine the paper presents a model of the fluid power pitch system, which is incorporated into the aeroelastic code FAST. Based on the model, an active damping approach is applied in combination with the standard pitch control to reduce oscillations in the pitch actuator force and hence the fatigue loadings on the mechanical structure. With basis in the implemented algorithm, the wind turbine is simulated under standard (IEC) load conditions and the load reduction possibilities analysed for the critical areas of the wind turbine along with performance of the wind turbine (pitch angle and power output).
Protect and Care (PaC) System for Lubrication Oil in Railway Applications
Authors: Fischer Götz , Schmitz Stefan 
Published: January 2016

In 2006, an automatic lube oil filtration system with an automatic backflushing filter and a centrifuge for railway engines was already presented at the ASME spring technical conference in Aachen. The technical benefit of a centrifuge compared to a cartridge filter is the ability to collect smaller particles.
The power to drive the centrifuge comes from the engine oil pressure. This engine oil pressure is dependent from the engine speed. Many operating profiles of locomotives are showing low engine speed and load e.g. while waiting in switchyard and under arctic weather conditions the engines keep idling even during “downtime”. Under those conditions a centrifuge is ineffective or even out of operation.
Extending Lean and EGR-Dilute Operating Limits of a Modern GDI Engine Using a Low-Energy Transient Plasma Ignition System
Authors: Sevik James , Wallner Thomas , Pamminger Michael , Scarcelli Riccardo , Singleton Dan , Sanders Jason 
Published: January 2016

The efficiency improvement and emissions reduction potential of lean and EGR dilute operation of spark-ignition gasoline engines is well understood and documented. However, dilute operation is generally limited by deteriorating combustion stability with increasing inert gas levels. The combustion stability decreases due to reduced mixture flame speeds resulting in significantly increased combustion initiation periods and burn durations.
A study was designed and executed to evaluate the potential to extend lean and EGR-dilute limits using a low-energy transient plasma ignition system. The low-energy transient plasma was generated by nano-second pulses and its performance compared to a conventional transistorized coil ignition system operated on an automotive, gasoline direct injection (GDI) single-cylinder research engine. The experimental assessment was focused on steady-state experiments at the part load condition of 1500 rpm 5.6 bar IMEP, where dilution tolerance is particularly critical to improving efficiency and emissions performance.
Experimental results suggest that the energy delivery process of the low-energy transient plasma ignition system significantly improves part load dilution tolerance by reducing the early flame development period. Statistical analysis of relevant combustion metrics was performed in order to further investigate the effects of the advanced ignition system on combustion stability. Results confirm that at select operating conditions EGR tolerance and lean limit could be improved by as much as 20% (from 22.7 to 27.1% EGR) and nearly 10% (from λ=1.55 to 1.7) with the low-energy transient plasma ignition system.
Friction Reduction Opportunities in Combustion Engine Crank Train Bearings
Authors: Aufischer Rainer , Walker Rick , Offenbecher Martin , Feng Oliver , Hager Gunther 
Published: January 2016

The development of combustion engines is heavily influenced by environmental regulations and efficiency. Since the environmental regulation have influenced engine design already with special combustion system and exhaust gas treatments, efficiency and the greenhouse gas CO2 has become a major issue for further development.
CO2 emissions and fuel efficiency are linked and are directly influenced by the internal friction of the combustion engine. One major part of this internal friction is coming from the crank train bearings. Since we have to consider different operating conditions for the crank train bearings like hydrodynamic and mixed friction (hydrodynamic in combination with boundary contact), working principles as well as different engine operating conditions like full load, idle, start stop etc. different measures need to be employed for a friction reduced crank train.
The optimal dimensioning of the bearings in combination with oil viscosity reduction are already known to a certain extent. Nevertheless they result in changes of bearing loads and may in consequence increase the share of boundary friction. Therefore, only looking on these two optimization steps is not enough. In addition the friction coefficient between bearing and shaft as well as the interaction between bearing surface and lubricant need to be addressed to reduce friction loss.
In order to gain a complete picture, influences and the interaction of
• geometric properties and bearing dimensions,
• friction coefficient of bearings in combination with crankshaft materials,
• oil formulation, viscosity and their interaction with engine application and duty cycle as well as
• losses caused by the lubrication system design and components
are investigated and analyzed based on simulation and testing. At first the different steps are investigated individually and secondly combinations and interactions are derived on basis of parameters derived on tribological tests and material data. Oil viscosity as major driver during hydrodynamic operation but also the influence of additive packages during mixed friction is roughly estimated on basis of tribological investigations.
Since the overall friction system and its optimization are very complex, an example for a truck engine in different applications shows advantages and disadvantages of the different approaches. Also border lines given by operational risk and improvement limits are explained. The improvement options given by bearing materials and special coatings are explained in combination with different engines and engine applications.
Further development activities, ways of collaboration between engine manufacturer and bearing supplier and an outlook on up-coming bearing system are completing the picture for a holistic approach on friction reduction in crank train bearings.
Development of a Methodology for Engine Performance Investigation Through Double Crankshaft Speed Measurement
Authors: Ponti F. , Ravaglioli V. , De Cesare M. 
Published: January 2016

Optimal combustion control has become a key factor in modern automotive applications to guarantee low engine out emissions and good driveability. In order to meet these goals, the engine management system has to guarantee an accurate control of torque delivered by the engine and optimal combustion phasing.
Both quantities can be calculated through a proper processing of in-cylinder pressure signal. However, in-cylinder pressure on-board installation is still uncommon, mainly due to problems related to pressure sensors’ reliability and cost. Consequently, over the last years, the increasing request for combustion control optimization spawned a great amount of research in the development of remote combustion sensing methodologies, i.e. algorithms that allow extracting useful information about combustion effectiveness via low cost sensors, such as crankshaft speed, accelerometers or microphones.
Based on the simultaneous acquisition of two crankshaft speed signals, this paper analyses the information that can be extracted about crankshaft’s torsional behavior through a proper processing of the acquired signals. In particular, the correlations existing between such information and indicated quantities (torque delivered by the engine and combustion phasing) have been analysed. In order to maximize the signal-to-noise ratio, each speed measurement has been performed at an end of the crankshaft, i.e. in correspondence of the flywheel and the distribution wheel. The presented approach has been applied to a light-duty L4 Diesel engine mounted in a test cell. Nevertheless, the methodology is general, and it can be applied to engines with a different number of cylinders, both CI and SI.
Exhaust Conditioning Technology to Prevent Sulfur Poisoning on Methane Oxidation Catalyst
Authors: Goenawan Isna Y. , Hu Linjie (Robin) , Williams Shazam 
Published: January 2016

In some regions of the world, emissions of total organic carbon (TOC), including methane and non-methane hydrocarbons (NMHCs), from the tail pipe of natural gas or biogas fuelled combustion equipments are strictly regulated (e.g. 150 mg/Nm3 of exhaust gas in Italy). Post combustor has been widely chosen in response to the TOC emission targets. TOC typically consists of >90% methane — a strong greenhouse gas and the most challenging compound to remove due to its highly stable form. Thus, more gas is being consumed to burn the TOC present in the exhaust, resulting in higher operating (or power production) costs.
A passive catalytic approach is an alternative to post combustor. Palladium based oxidation catalyst is known to actively remove TOC, providing no sulfur compounds present. Sulfur poisons and deactivates the catalyst in a short time. This paper presents a concept to extend the life of the oxidation catalyst by using an exhaust post conditioning system. The system is designed to eliminate and withstand contaminants, yielding a protection to the catalyst. Consequently, the catalyst life is prolonged by about 50 times.
Simulation of Mechanical Hydraulic System Dynamics Using Coupled Specialized Fluid Models and Multibody Dynamics
Authors: Lynch Bradford 
Published: January 2016

Durability is a prime concern in the design of hydraulic systems and fuel injectors [1–3] thus an accurate prediction of impact velocities between components and the flow through them is essential to assessing concepts. Simulation of these systems is difficult because the geometries are complex, some volumes go to zero as the components move, and the flow at a single operating condition generally spans Reynolds numbers less than 1 to more than 104[4–8]. As a result of these challenges, experimental testing of prototypes is the dominant method for comparing concepts. This approach can be effective but is far more costly, time consuming, and less flexible than the ability to run simulations of concepts early in the design cycle.
A validated model of a fuel injector built from publicly available data [1] is used to present a new approach to modelling hydraulic systems which overcomes many of these obstacles. This is accomplished by integrating several commercially available tools to solve the physics specific to each area within the fuel injector. First, the fuel injector is simulated using a 3D CFD simulation integrated with a 1D CFD system model. The flow in various regions of the injector is then analyzed to determine if the fluid models in these areas can be simplified based on the flow regime. Based on this analysis, a combination of models is assembled to improve the quality of the simulation while decreasing the time required to run the model.
The fuel injector is simulated using a multibody dynamics model coupled to a reluctance network model of the solenoid and several fluid models. The first is a 3D CFD simulation which uses novel mesh refinement techniques during runtime to ensure high mesh quality throughout the motion of components, to resolve the velocity profile of laminar flows, and to satisfy the requirements of the RNG k-ε turbulence model and wall functions. This approach frees the analyst from defining the mesh before runtime and instead allows the mesh to adapt based on the flow conditions in the simulation. Due to the highly efficient meshing algorithm employed, it is possible to re-mesh at each timestep thus ensuring a high quality structured mesh throughout the simulation duration. Then a 3D FEM solution to the Reynolds Equation and a statistical contact model is employed to solve for the squeeze films between components and to allow separation and contact between bodies in the control valve. These detailed simulations are integrated with a 1D flow model of the fuel injection system.
The results from the detailed coupled simulations are compared to the results from simpler 1D models and measured data to illustrate under which operating conditions a more advanced technique incorporating 3D CFD is worth the additional computational expense versus a traditional 1D model.
A Biogas-Tolerant Engine-Generator for Advanced Agricultural Waste Management
Authors: Yelvington Paul E. , Gattoni John M. , Merical Kyle I. , Carpenter Andrew L. 
Published: January 2016

Anaerobic digesters are capable of producing methane-rich biogas from animal manure and also offer the advantages of controlling odors, reducing pathogens, and minimizing the environmental impact of the waste. Unfortunately, biogas is contaminated with hydrogen sulfide (H2S), a highly corrosive gas that is not compatible with many stock engine component materials. As a result, conventional engines can fail after several months of exposure to raw biogas. No small or medium piston engine-generators (<100 kWe) are currently available that can use this fuel without pretreatment to remove the H2S — a process that adds complexity, cost, consumables, and maintenance. As a result, many smaller digester installations simply flare the biogas rather than extracting any useful work from the fuel.
Mainstream Engineering is developing a biogas-tolerant engine-generator (BTEG) that can use raw biogas without pretreatment to remove H2S. The development program involved a combination of approaches — materials replacement, coatings, engine control strategy changes, lubrication system changes, and additional sensors. A prototype 25 kW BTEG has been developed using a Ford DSG 2.3 L natural gas engine as the demonstration platform. In this paper, we report on performance testing of the baseline unmodified engine-generator and the BTEG. Measurements of fuel consumption, exhaust temperature, in-cylinder pressure, and exhaust gaseous emissions were made using several synthetic biogas mixtures (60–80% CH4/balance CO2) and pure methane. Because the methane fraction in biogas can change with digester conditions and weather — a method of estimating the biogas composition on the fly and adjusting the spark timing to compensate for the variability has been demonstrated. We also report on limited (100 hr) durability testing of the modified engine using fuel containing 3,000 ppmv of H2S. During this test, the oil was analyzed to track acidification of the engine oil and monitor the accumulation of sulfur or any wear metals.