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Novel inferences of ionisation and recombination for particle/power balance during detached discharges using deuterium Balmer line spectroscopy
No full textThe physics of divertor detachment is determined by divertor power, particle and momentum balance. This work provides a novel analysis technique of the Balmer line series to obtain a full particle/power balance measurement of the divertor. This supplies new information to understand what controls the divertor target ion flux during detachment. Atomic deuterium excitation emission is separated from recombination quantitatively using Balmer series line ratios. This enables analysing those two components individually, providing ionisation/recombination source/sinks and hydrogenic power loss measurements. Probabilistic Monte Carlo techniques were employed to obtain full error propagation?eventually resulting in probability density functions for each output variable. Both local and overall particle and power balance in the divertor are then obtained. These techniques and their assumptions have been verified by comparing the analysed synthetic diagnostic ?measurements? obtained from SOLPS simulation results for the same discharge. Power/particle balance measurements have been obtained during attached and detached conditions on the TCV tokamak.SP
Scalable closed-form trajectories for periodic and non-periodic human-like walking
No full textWe present a new framework to generate humanlike lower-limb trajectories in periodic and non-periodic walking. In our method, walking dynamics is encoded in 3LP, a linear simplified model composed of three pendulums to simulate falling, swing, and torso balancing dynamics. To stabilize the motion, we use an optimal time-projecting controller which suggests new footstep locations. On top of gait generation and stabilization in the simplified space, we introduce a kinematic conversion that synthesizes more humanlike trajectories by combining geometric variables of the 3LP model adaptively. Without any tuning, numerical optimization or off-line data, our walking gaits are scalable with respect to body properties and gait parameters. We can change body mass and height, walking direction, speed, frequency, double support time, torso style, ground clearance, and terrain inclinations. We can also simulate constant external dragging forces or momentary perturbations. The proposed framework offers closed-form solutions with simulation speeds orders of magnitude faster than real time. This can be used for video games and animations on portable electronic devices with limited power. It also gives insights for generation of more human-like walking gaits on humanoid robots.BIOROBLAS
Efficient photosynthesis of carbon monoxide from CO2 using perovskite photovoltaics
No full textArtificial photosynthesis, mimicking nature in its efforts to store solar energy, has received considerable attention from the research community. Most of these attempts target the production of H-2 as a fuel and our group recently demonstrated solar-to-hydrogen conversion at 12.3% efficiency. Here, in an effort to take this approach closer to real photosynthesis, which is based on the conversion of CO2, we demonstrate the efficient reduction of CO2 to carbon monoxide driven solely by simulated sunlight using water as the electron source. Employing series-connected perovskite photovoltaics and high-performance catalyst electrodes, we reach a solar-to-CO efficiency exceeding 6.5%, which represents a new benchmark in sunlight-driven CO2 conversion. Considering hydrogen as a secondary product, an efficiency exceeding 7% is observed. Furthermore, this study represents one of the first demonstrations of extended, stable operation of perovskite photovoltaics, whose large open-circuit voltage is shown to be particularly suited for this process.LP
Additive manufacturing of a precious bulk metallic glass
No full textFor the first time, a high-density amorphous and crack-free bulk metallic glass (BMG) based on a precious metal (PdCuNiP) was produced via additive manufacturing (AM). Laser powder-bed fusion (LPBF) was used for the fabrication of the samples, and led to a density of 99.6%. Excellent mechanical properties such as high hardness and compressive strength were achieved, overcoming the limitations usually found for precious metals in jewelry and watchmaking. Furthermore, without any post-processing, a mirror-like smooth and brilliant surface was directly obtained, which is highly beneficial for applications where surface finish or aesthetics matters. The effect of the main processing parameters, such as laser power and laser-scanning speed, on the shape of single tracks was investigated by laser confocal microscopy (LCM). Following the single-track experiments, highly amorphous LPBF samples were produced. The samples were characterized by optical microscopy (OM), scanning electron microscopy (SEM), conventional and synchrotron X-ray diffraction (XRD), micro-computed tomography (μ-CT), compression tests, and microhardness. The crystallization kinetics of the powder alloy was investigated via fast differential scanning calorimetry (FDSC). A small quantity of the powder (< 70 g) was used for the fabrication of samples, alleviating the cost of the process. Efficient production of precious metal parts with enhanced mechanical properties is demonstrated.LMT
The Battle of the Schedulers: FreeBSD ULE vs. Linux CFS
No full textThis paper analyzes the impact on application performance of the design and implementation choices made in two widely used open-source schedulers: ULE, the default FreeBSD scheduler, and CFS, the default Linux scheduler. We compare ULE and CFS in otherwise identical circumstances. We have ported ULE to Linux, and use it to schedule all threads that are normally scheduled by CFS. We compare the performance of a large suite of applications on the modified kernel running ULE and on the standard Linux kernel running CFS. The observed performance differences are solely the result of scheduling decisions, and do not reflect differences in other subsystems between FreeBSD and Linux. There is no overall winner. On many workloads the two schedulers perform similarly, but for some workloads there are significant and even surprising differences. ULE may cause starvation, even when executing a single application with identical threads, but this starvation may actually lead to better application performance for some workloads. The more complex load balancing mechanism of CFS reacts more quickly to workload changes, but ULE achieves better load balance in the long run.LABO
Soft masses in superstring models with anomalous U(1) symmetries
No full textWe analyze the general structure of soft scalar masses emerging in superstring models involving anomalous U(1) symmetries, with the aim of characterizing more systematically the circumstances under which they can happen to be flavor universal. We consider both heterotic orbifold and intersecting brane models, possibly with several anomalous and non-anomalous spontaneously broken U(1) symmetries. The hidden sector is assumed to consist of the universal dilaton, Kahler class and complex structure moduli, which are supposed to break supersymmetry, and a minimal set of Higgs fields which compensate the Fayet-Iliopoulos terms. We leave the superpotential that is supposed to stabilize the hidden sector fields unspecified, but we carefully take into account the relations implied by gauge invariance and the constraints required for the existence of a metastable vacuum with vanishing cosmological constant. The results are parametrized in terms of a constrained Goldstino direction, suitably defined effective modular weights, and the U(1) charges and shifts. We show that the effect induced by vector multiplets strongly depends on the functional form of the Kahler potential for the Higgs fields. We find in particular that whenever these are charged matter fields, like in heterotic models, the effect is non-trivial, whereas when they are shifting moduli fields, like in certain intersecting brane models, the effect may vanish.GR-S
numerical modelling of macrosegregation using multiple, adaptive finite element grids
No full textLSM
Factors Affecting Sumedang Regency Bawaslu Performance in 2022 Panwascam Selection Activities
Get PDFThis study aims to find out and analyze data regarding the performance of Sumedang Regency Bawaslu members in the 2022 Panwascam selection activities. This research was conducted using a qualitative method. The sampling technique used was purposive sampling, with five informants. Data collection techniques include observation, interviews and documentation. Research data were obtained through techniques: data reduction, data presentation, conclusion drawing which aims to obtain data to support the final research results. The results of the research conducted on the performance of the Sumedang Regency Bawaslu in Panwascam selection from the dimensions of service quality, responsiveness and accountability can be said to be good, seen from the ability of Bawaslu to provide services, provide assistance to prospective members, and have clear guidelines and sanctions. However, from the dimensions of productivity and responsibility it is still said to be lacking due to the lack of representation of women, the presence of members of political parties who have registered and the lack of clarity about the division of individual tasks within the working group. Suggestions in this research include increasing work effectiveness by carrying out socialization activities for women related to Panwascam activities, improving the quality of Bawaslu officers to minimize the participation of political parties and making written rules regarding the division of individual work in working groups. For written research sources, further research regarding the implementation of staffing policies in improving employee performance
Laws of order
No full textBuilding correct and efficient concurrent algorithms is known to be a difficult problem of fundamental importance. To achieve efficiency, designers try to remove unnecessary and costly synchronization. However, not only is this manual trial-and-error process ad-hoc, time consuming and error-prone, but it often leaves designers pondering the question of: is it inherently impossible to eliminate certain synchronization, or is it that I was unable to eliminate it on this attempt and I should keep trying? In this paper we respond to this question. We prove that it is impossible to build concurrent implementations of classic and ubiquitous specifications such as sets, queues, stacks, mutual exclusion and read-modify-write operations, that completely eliminate the use of expensive synchronization. We prove that one cannot avoid the use of either: i) read-after-write (RAW), where a write to shared variable A is followed by a read to a different shared variable B without a write to B in between, or ii) atomic write-after-read (AWAR), where an atomic operation reads and then writes to shared locations. Unfortunately, enforcing RAW or AWAR is expensive on all current mainstream processors. To enforce RAW, memory ordering--also called fence or barrier--instructions must be used. To enforce AWAR, atomic instructions such as compare-and-swap are required. However, these instructions are typically substantially slower than regular instructions. Although algorithm designers frequently struggle to avoid RAW and AWAR, their attempts are often futile. Our result characterizes the cases where avoiding RAW and AWAR is impossible. On the flip side, our result can be used to guide designers towards new algorithms where RAW and AWAR can be eliminated.DC