Towards Energy-Efficient Electrified Mobile Hydraulics : Considering Varying Application Conditions

In the face of global warming, companies in all kinds of industries need to take measures to reduce the use of fossil fuels, which is explicitly enforced by more and more upcoming emission legislation in many countries. In the case of heavy-duty mobile machines (HDMMs), a currently high-emitting sector, the most feasible method of reducing harmful emissions during operation is battery-based electrification. However, the relatively low capacities and high costs of available battery packs are restricting the operation times as well as upper power limits of battery-electric HD-MMs—at least under economically feasible conditions. In this scenario, the typically low energy-efficiencies of conventional hydraulic systems, which are essential for realizing linear actuation on HDMMs, are becoming more critical than ever before, and more efficient alternative concepts are required. As an answer to this demand, this thesis and the six publications on which it is based analyze how alternative hydraulic concepts for electrified HDMMs should look like, and two specific concepts are proposed as well as evaluated. In this scope, the focus is not only on improving the efficiency but also on other aspects that can prevent or accelerate the success of alternative hydraulic concepts on the market, such as costs and feasibility. Since those aspects cannot be analyzed in isolation from the application conditions, the essential characteristics of HDMMs and the differences of those characteristics between HDMM types are elaborated systematically. Furthermore, the implications of the transition from internal combustion engines (ICEs) to electric machines (EMs) as the prime movers for hydraulic pumps are identified by means of a literature review. Considering the insights from the analyses of those aspects, already existing hydraulic concepts—i.e., conventional as well as proposed alternatives for improved efficiency—are reevaluated, and beneficial elements of those concepts are filtered out for constructing two new concepts. Those two proposed concepts are characterized by a modular approach in which actuators can be valve-controlled, which might be less efficient but more cost-effective, or pump-controlled, as an alternative for more efficient yet costly actuation of selected functions on the HDMM. Simulation studies are used to demonstrate the efficiency of both concepts under varying configurations that are enabled through the modular nature of the concepts, and the differences in applying them on a telehandler, wheel loader, or excavator are analyzed. For the second concept, which is based on displacement-control and performed best in the simulations, a cost analysis is used to prove additionally that reasonably short payback times of the increased investment costs can be reached in different scenarios. Furthermore, the efficiency performance as well as feasibility—in terms of using commercially available components only and achieving good controllability—are experimentally validated on a telehandler

A closed circuit electro-hydraulic actuator with energy recuperation capability

The recent electrification trend in the off-road market has incentivized research towards the proposal of compact, cost-effective and energy-efficient solutions for hydraulic actuators. As a result, increased attention has been given to electro-hydraulic actuator (EHA) architectures. The paper offers a study performed on a novel closed-circuit EHA architecture with the goal to maximize the overall system efficiency while meeting or exceeding traditional off-road applications performance, thereby enabling further electrification of off-road applications. Both numerical and experimental approaches are utilized to validate the functionality of the proposed EHA circuital configuration in four quadrants. Moreover, the actuator functionality at both high and low velocities are considered, which has never been explored in the past due to the limitations on the hydraulic machine driving speed. The good match between the experimental data and the simulation results confirms the potential of the simulation model for sizing such EHA architecture for different actuator sizes, duty cycles, and performance levels

The reversal of the SF-density relation in a massive, X-ray selected galaxy cluster at z=1.58: results from Herschel

Dusty, star-forming galaxies have a critical role in the formation and evolution of massive galaxies in the Universe. Using deep far-infrared imaging in the range 100-500um obtained with the Herschel telescope, we investigate the dust-obscured star formation in the galaxy cluster XDCP J0044.0-2033 at z=1.58, the most massive cluster at z >1.5, with a measured mass M200= 4.7x10$^{14}$ Msun. We perform an analysis of the spectral energy distributions (SEDs) of 12 cluster members (5 spectroscopically confirmed) detected with >3$\sigma$ significance in the PACS maps, all ULIRGs. The individual star formation rates (SFRs) lie in the range 155-824 Ms/yr, with dust temperatures of 24$\pm$35 K. We measure a strikingly high amount of star formation (SF) in the cluster core, SFR ( 1875$\pm$158 Ms/yr, 4x higher than the amount of star formation in the cluster outskirts. This scenario is unprecedented in a galaxy cluster, showing for the first time a reversal of the SF-density relation at z~1.6 in a massive cluster.Comment: Letter accepted for publication in MNRAS, ESA Press Release on 18 December 201

Experimental Investigations of Partially Valve-, Partially Displacement-Controlled Electrified Telehandler Implements

The next generation of electrified heavy-duty mobile machines (HDMMs) requires more efficient hydraulic systems—to save energy and to compensate for the limited capacities of available mobile electric energy sources. This study is experimentally demonstrating the functionality, dynamic performance, and efficiency of such a more efficient but also cost-effective system. The demonstrator is a conventional nine-tonne telehandler that has been transformed by replacing the diesel engine with an electric machine (EM) and changing the boom function from valve to displacement control. Since the system control and the resulting dynamics are not trivial, key aspects of it are explained in the paper. With the functional system, achievable consumption reductions could be obtained by measuring five different representative work cycles repeatedly and comparing the average consumption values to the consumption of a purely valve-controlled but also electrified reference version. In four of five cycles, an average reduction of 21–31% was achieved, which confirms the simulation results from previous studies and the effectiveness of the concept. However, one cycle—characterized by serial movements and longer breaks of the boom movement—showed a reduction of only 3% and that the effectiveness of the concept can also be lower in certain cases that depend mainly on the operator.publishedVersionPeer reviewe

Improving the Energy Efficiency of Single Actuators with High Energy Consumption : An Electro-Hydraulic Extension of Conventional Multi-Actuator Load-Sensing Systems

A load sensing (LS) supply in combination with control valves is one of the most common solutions for the actuation of implements on heavy-duty mobile machines (HDMMs). A major drawback of this approach is its relatively low energy efficiency due to metering losses—especially for multi-actuator operation and load braking. Several novel, more efficient concepts have already been proposed but involve high component costs for each actuator, which is not acceptable for HDMMs with many actuators that have a medium to low energy turnover. Therefore, this work proposes a novel system design which is based on a conventional LS system—for cheap operation of a high number of low-energy-consuming actuators—but allows to avoid metering losses for single high-energy-consuming actuators by replacing their metering valves with electric-generator-hydraulic-motor (EGHM) units that work similar to pump-controlled concepts. The benefits of the novel concept are explained in detail by looking at the three main throttling functions of an actuator in a typical valvecontrolled LS systems, which the novel concept avoids by applying pressure in the actuator return lines and recuperating energy electrically instead of dissipating it by throttling. Furthermore, advantages and challenges for the novel concept are analyzed, and ways to address the latter are presented. Before the novel concept is simulated, the required control algorithms are presented. The simulation study in Amesim and Simulink focuses on a telehandler that utilizes the novel concept for the boom, extension and tilt actuators. Simulation results show that the novel system can decrease the required input energy for typical duty cycles by up to 34% compared to a conventional LS system. At the same time, simulations show that, from an economic perspective, it seems most reasonable to utilize the novel EGHM units only for the boom and extension actuators of the studied telehandler.acceptedVersionPeer reviewe

Case report: cerebral sinus vein thrombosis in two patients with AstraZeneca SARS-CoV-2 vaccination

SARS-CoV-2 infection is associated with an increased rate of thromboembolic events and mortality. Diferent vaccines are globally used to limit the pandemic. In this report, we present the case of two young female patients with newly diagnosed cerebral sinus vein thrombosis occurring after injection of the vector-based ChAdOx1 vaccine. Both patients presented with unusual headache only. The two of them used an estrogen-containing contraception, had had a history of deep venous thrombosis, and both had MTHFR mutations. Both patients developed SARS-CoV-2 specifc humoral and cellular immunity including both CD4 and CD8 T cells. This rare, but serious complication needs to be considered after vaccination of young females, even if there is no evidence of heparin-induced thrombocytopenia

Self-similar scaling and evolution in the galaxy cluster X-ray Luminosity-Temperature relation

We investigate the form and evolution of the X-ray luminosity-temperature (LT) relation of a sample of 114 galaxy clusters observed with Chandra at 0.1<z<1.3. The clusters were divided into subsamples based on their X-ray morphology or whether they host strong cool cores. We find that when the core regions are excluded, the most relaxed clusters (or those with the strongest cool cores) follow an LT relation with a slope that agrees well with simple self-similar expectations. This is supported by an analysis of the gas density profiles of the systems, which shows self-similar behaviour of the gas profiles of the relaxed clusters outside the core regions. By comparing our data with clusters in the REXCESS sample, which extends to lower masses, we find evidence that the self-similar behaviour of even the most relaxed clusters breaks at around 3.5keV. By contrast, the LT slopes of the subsamples of unrelaxed systems (or those without strong cool cores) are significantly steeper than the self-similar model, with lower mass systems appearing less luminous and higher mass systems appearing more luminous than the self-similar relation. We argue that these results are consistent with a model of non-gravitational energy input in clusters that combines central heating with entropy enhancements from merger shocks. Such enhancements could extend the impact of central energy input to larger radii in unrelaxed clusters, as suggested by our data. We also examine the evolution of the LT relation, and find that while the data appear inconsistent with simple self-similar evolution, the differences can be plausibly explained by selection bias, and thus we find no reason to rule out self-similar evolution. We show that the fraction of cool core clusters in our (non-representative) sample decreases at z>0.5 and discuss the effect of this on measurements of the evolution in the LT relation.Comment: 21 pages, 15 figures. Submitted to MNRAS. Comments welcom

An Operational Overview of the EXport Processes In the Ocean From RemoTe Sensing (EXPORTS) Northeast Pacific Field Deployment

The goal of the EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) field campaign is to develop a predictive understanding of the export, fate, and carbon cycle impacts of global ocean net primary production. To accomplish this goal, observations of export flux pathways, plankton community composition, food web processes, and optical, physical, and biogeochemical (BGC) properties are needed over a range of ecosystem states. Here we introduce the first EXPORTS field deployment to Ocean Station Papa in the Northeast Pacific Ocean during summer of 2018, providing context for other papers in this special collection. The experiment was conducted with two ships: a Process Ship, focused on ecological rates, BGC fluxes, temporal changes in food web, and BGC and optical properties, that followed an instrumented Lagrangian float; and a Survey Ship that sampled BGC and optical properties in spatial patterns around the Process Ship. An array of autonomous underwater assets provided measurements over a range of spatial and temporal scales, and partnering programs and remote sensing observations provided additional observational context. The oceanographic setting was typical of late-summer conditions at Ocean Station Papa: a shallow mixed layer, strong vertical and weak horizontal gradients in hydrographic properties, sluggish sub-inertial currents, elevated macronutrient concentrations and low phytoplankton abundances. Although nutrient concentrations were consistent with previous observations, mixed layer chlorophyll was lower than typically observed, resulting in a deeper euphotic zone. Analyses of surface layer temperature and salinity found three distinct surface water types, allowing for diagnosis of whether observed changes were spatial or temporal. The 2018 EXPORTS field deployment is among the most comprehensive biological pump studies ever conducted. A second deployment to the North Atlantic Ocean occurred in spring 2021, which will be followed by focused work on data synthesis and modeling using the entire EXPORTS data set

Differential Effects of Isoflurane and Propofol on Upper Airway Dilator Muscle Activity and Breathing

Background: Anesthesia impairs upper airway integrity, but recent data suggest that low doses of some anesthetics increase upper airway dilator muscle activity, an apparent paradox. The authors sought to understand which anesthetics increase or decrease upper airway dilator muscle activity and to study the mechanisms mediating the effect. Methods: The authors recorded genioglossus electromyogram, breathing, arterial blood pressure, and expiratory carbon dioxide in 58 spontaneously breathing rats at an estimated ED 50 (median effective dose) of isoflurane or propofol. The authors further evaluated the dose-response relations of isoflurane under different study conditions: (1) normalization of mean arterial pressure, or end-expiratory carbon dioxide; (2) bilateral lesion of the Kölliker-Fuse nucleus; and (3) vagotomy. To evaluate whether the markedly lower inspiratory genioglossus activity during propofol could be recovered by increasing flow rate, a measure of respiratory drive, the authors performed an additional set of experiments during hypoxia or hypercapnia. Results: In vagally intact rats, tonic and phasic genioglossus activity were markedly higher with isoflurane compared with propofol. Both anesthetics abolished the genioglossus negative pressure reflex. Inspiratory flow rate and anesthetic agent predicted independently phasic genioglossus activity. Isoflurane dose-dependently decreased tonic and increased phasic genioglossus activity, and increased flow rate, and its increasin