Huppler K.,TPC |
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014
To accommodate differences in systems architecture and DBMS functions and features, the TPC has long held that the best way to define a database benchmark is to author a paper specification of the application to be measured, leaving the implementation of that specification to the individual analyst. While this technique allows for the optimal implementation for a specific DBMS on a specific platform, it makes the initial entry into benchmark development a costly one - often cost prohibitive. The TPC has embarked on a plan to develop a new benchmark category, dubbed TPC Express, where benchmarks based on predefined, executable kits that can be rapidly deployed and measured. This paper defines the TPC Express model, contrasts it to the TPC's existing "Enterprise" model, and highlights many of the changes needed within the TPC to ensure the Express model is a successful one. © 2014 Springer International Publishing Switzerland.
Although the theory of quantum chromodynamics (QCD) provides us with an understanding of the foundation of the nuclear force, this binding interaction in nuclei operates at low energy, where the force is strong and difficult to calculate directly from the theory (see ref. 5 and references therein for recent developments). For that reason, a common parameterization of the effective interaction between nucleons is based on experimental measurements, and the corresponding parameterization for antinucleons remains undetermined. The important paramfeters in such a description of the interaction are the scattering length (f ), which is related to elastic cross-sections, and the effective range of the interaction (d ), which is determined to be a few femtometres (the typical nuclear scale). For a short range potential, these two parameters are related to the s-wave scattering phase shift δ and the collision momentum k by . The existence and production rates of antinuclei offer indirect information about interactions between antinucleons, and also have relevance to the unexplained baryon asymmetry in the Universe6. Antinuclei produced to date include antiprotons, antideuterons, antitritons, antihelium-3, and the recently discovered antihypertriton and antihelium-4 (see ref. 1 and references therein). The interaction between two antinucleons is the basic interaction that binds the antinucleons into antinuclei, and this has not been directly measured previously. Of equal importance, one aspect of the current measurement is a test of matter–antimatter symmetry, more formally known as CPT—a fundamental symmetry of physical laws under the simultaneous transformations of charge conjugation (C), parity transformation (P) and time reversal (T). Although various prior CPT tests7 have been many orders of magnitude more precise than what is reported here, there is value in independently verifying each distinct prediction of CPT symmetry7. Ultra-relativistic nuclear collisions produce an energy density similar to that of the Universe microseconds after the Big Bang, and the high energy density creates a favourable environment for antimatter production. The abundantly produced antiprotons provide the opportunity to measure, for the first time, the parameters ƒ and d of the strong nuclear force between antinucleons rather than nucleons. The technique used to probe the antiproton–antiproton interaction involves momentum correlations, and it resembles the space-time correlation technique used in HBT (Hanbury Brown and Twiss) intensity interferometry. Since its invention for use in astronomy in the 1950s4, the HBT technique has been adopted in many areas of physics, including the study of the quantum state of Bose–Einstein condensates8, and the correlation among electrons9 and among atoms in cold Fermi gases10. A Bose–Einstein enhancement in particle physics was first observed in the late 1950s as an enhanced number of pairs of identical pions produced with small opening angles, the GGLP (Goldhaber, Goldhaber, Lee and Pais) effect11. Later on, Kopylov and Podgoretsky noted the common quantum statistics origin of the HBT and GGLP effects12, and, through a series of papers (see a review13 and references therein), they devised the basics of the momentum correlation interferometry technique. In this technique, they introduced the correlation functions (CFs) as ratios of the momentum distributions of correlated and uncorrelated particles, with C = 1 for no correlations, suggested the so-called mixing technique to construct the uncorrelated distribution by using particles from different collisions (events), and formulated a simple relation of the CFs with the space-time structure of the particle emission region. Here C(p , p ) is the correlation function, P(p ) and P(p ) are probabilities for detecting a particle with momentum p and a particle with momentum p , respectively, and P(p , p ) is the joint probability for detecting both simultaneously. As a result, the momentum correlation technique has been widely embraced by the nuclear physics community14, 15, 16, 17. Figure 1 illustrates the process of constructing two-particle correlations in heavy-ion collisions. In addition to quantum statistics effects, final state interactions (FSIs) play an important role in the formation of correlations between particles. FSIs include, but are not limited to, the formation of resonances, the Coulomb repulsion effect, and the nuclear interactions between two particles14, 15, 18, 19. In fact, FSI effects provide valuable additional information. They allow for (see refs 16, 20 and references therein) coalescence femtoscopy, correlation femtoscopy with non-identical particles, including access to the relative space-time production asymmetries, and a measurement of the strong interaction between specific particles. The last measurement is often difficult to access by other means and is the focus of this paper (for recent studies see refs 21, 22). In a semi-classical geometrical description, a complex heavy-ion collision can be regarded as a superposition of many individual nucleon–nucleon collisions, each governed by a constant probability of interaction with all nucleons travelling in straight lines. The centrality corresponds to the extent that two nuclei overlap, and events are categorized by their centrality, based on the observed number of tracks emitted from each collision. Zero per cent centrality corresponds to exactly head-on collisions which produce the most tracks, while 100% centrality corresponds to barely glancing collisions which produce the fewest tracks. The data used here consists of Au + Au collisions at a centre-of-mass energy of 200 GeV per nucleon pair, taken during the operation of RHIC in the year 2011. In total, 500 million events were taken by the minimum-bias trigger at STAR. This trigger selects all particle-producing collisions, regardless of the extent of overlap of the incident nuclei, but with a requirement that collisions must have occurred along the trajectory of the colliding Au ion and within ±30 cm of the centre of STAR’s Time Projection Chamber (TPC)23. Events used in this analysis correspond to the 30%–80% centrality class, for which the signal due to two-particle interaction is stronger than that from smaller centrality classes, while particle yields are larger than that from larger centrality classes. The two main detectors used in the measurement are the STAR TPC and the Time of Flight Barrel (TOF)24. The TPC is situated in a solenoidal magnetic field (0.5 T), and it provides a three-dimensional image of the ionization trails left along the path of charged particles. The TOF encloses the curved surface of the cylindrical TPC. In conjunction with the momentum measured via the track curvature in TPC, particle identification (PID) is achieved by two key measurements: the mean energy loss per unit track length, 〈dE/dx〉, which can be used to distinguish particles with different masses or charges, and the time of flight of particles reaching the TOF detector, which can be used, together with tracking information, to derive the square of a particle’s mass (m2). Figure 2 shows a typical calculated mass-squared (m2) distribution versus (see Fig. 2 legend) for antiprotons. The population distribution of (anti)proton pairs as a function of (anti)proton momentum (k*) in the pair rest frame (in which the centre of mass of the pair is at rest, convenient for carrying out measurements) is measured for the correlated pairs from within the same event, A(k*), and, separately, for the non-correlated pairs from two different (mixed) events, B(k*). The former corresponds to the joint probability P(p , p ), and the latter corresponds to the product of two probabilities, P(p )P(p ), where P(p ) and P(p ) each corresponds for observing single (anti)protons. The ratio of the two, A(k*)/B(k*), gives the measured CF (see Methods). The observed (anti)protons can come from weak decays of already correlated primary particles, hence introducing residual correlations which contaminate the CF. The dominant contaminations to the CF come from the p–Λ ( ) and Λ–Λ ( ) correlations (where p and Λ denotes the proton and lambda particle, respectively, and and denotes the corresponding antiparticle), and are taken into account by fitting the CF with corresponding contributions. Taking the two-proton correlation measurement as an example25, where C (k*) is the inclusive CF, and C (k*; R ) is the true proton–proton CF, which can be described by the Lednický and Lyuboshitz analytical model19. In this model, for given s-wave scattering parameters, the correlation function with FSI is calculated as the square of the properly symmetrized wavefunction averaged over the total pair spin and the distribution of relative distances of particle emission points in the pair rest frame (see Methods). are the residual CFs which are expressed through the p–Λ and Λ–Λ CFs, and , using integral transformation25 from and to (see Methods). is taken from a theoretical calculation19, which includes all final-state interactions and explains experimental data well21. is from an experimental measurement corrected for mis-identified Λs (ref. 22). R and R , assumed to be the same numerically, are the invariant Gaussian radii21 from the proton–proton correlation and the proton–Λ correlation, respectively. x , x and x , taken from the THERMINATOR2 model26, are the relative contributions from pairs with both daughters from the primary collision, pairs with one daughter from the primary collision and the other one from a Λ decay, and pairs with both daughters from a Λ decay, respectively. Figure 3 shows the CF for proton–proton pairs (Fig. 3a) and antiproton–antiproton pairs (Fig. 3b), for the 30%–80% centrality class of Au + Au collisions at a centre-of-mass energy of 200 GeV per nucleon pair. The proton–proton CF exhibits a maximum at k* ≈ 0.02 GeV c−1 due to the attractive singlet s-wave interaction between the two detected protons and is consistent with previous measurements27. The antiproton–antiproton CF shows a similar structure with the maximum appearing at the same k* value. In Fig. 3c, the ratio of the inclusive CF for proton–proton pairs to that of antiproton–antiproton pairs is presented. It is well centred at unity for almost all the k* range, except for the region k* < 0.02 GeV c−1, where the error becomes large. This indicates that the strong interaction is indistinguishable within errors between proton–proton pairs and antiproton–antiproton pairs. By fitting the CF with equation (1), we determine the singlet s-wave scattering length and effective range for the antiproton–antiproton interaction to be f = 7.41 ± 0.19(stat.) ± 0.36(sys.) fm and d = 2.14 ± 0.27(stat.) ± 1.34(sys.) fm, respectively. Here stat. and sys. indicate statistical and systematic errors, respectively. The extracted radii for protons (R ) and that for antiprotons ( ) are 2.75 ± 0.01(stat.) ± 0.04(sys.) fm and 2.80 ± 0.02(stat.) ± 0.03(sys.) fm, respectively. Figure 4 presents the first measurement of the antiproton–antiproton interaction, together with prior measurements for nucleon–nucleon interactions. Within errors, the f and d for the antiproton–antiproton interaction are consistent with their antiparticle counterparts—the ones for the proton–proton interaction. Our measurements provide parameterization input for describing the interaction among cold-trapped gases of antimatter ions, as in an ultracold environment, where s-wave scattering dominates and effective-range theory shows that the scattering length and effective range are parameters that suffice to describe elastic collisions. The result provides a quantitative verification of matter–antimatter symmetry in the important and ubiquitous context of the forces responsible for the binding of (anti)nuclei. Possible future improvement of the measurement could be made by reducing the uncertainty from the Λ–Λ CF (C (k*)), which dominates our systematic error, by further accumulation of data. In addition, a similar extraction of f and d could also be repeated with (anti)proton–(anti)proton CF28 measured at the Large Hadron Collider, where the yield ratio of antiproton to proton is close to unity.
« London Hydrogen Network Expansion project sets two new FCEV records | Main | Honda delivers first Clarity Fuel Cell to Japanese Ministry of Economy, Trade and Industry » Daimler Trucks demonstrated the new Highway Pilot Connect system for autonomous truck platooning on the A52 autobahn near Düsseldorf. Three WiFi-connected, autonomously driving trucks operated on the autobahn with authorization for public traffic in a platoon formation. Such a combination can reduce fuel consumption by up to 7% and the road space requirement on motorways by almost half, while improving traffic safety at the same time, Daimler said. Based on the Daimler Trucks Highway Pilot system for autonomously driving heavy trucks (earlier post), the three trucks link up to form an aerodynamically optimized, fully automated platoon. Connected vehicles in a platoon require a distance of only 15 meters instead of 50 meters between them. This considerably smaller distance produces a significant reduction in aerodynamic drag—comparable to slipstream riding in cycling competitions. In this way a platoon of three trucks can achieve the ~7% fuel saving, resulting in fuel consumption figures of around 25 l/100 km (9.4 mpg) possible for a loaded semitrailer combination with a gross weight of 40 t. This corresponds to a consumption of only 0.66 l/100 km (356 mpg) per tonne, or CO emissions of 13.3 g per kilometer per tonne. In parallel with this, platooning allows much more efficient use of the road space: thanks to the shorter distance between vehicles, a platoon of three linked trucks has a length of only 80 meters. In contrast to this, three trucks which are not electronically docked require a total of 150 meters of road space. At the same time platooning makes road traffic much safer: while a human behind the wheel has a reaction time of 1.4 seconds, Highway Pilot Connect transmits braking signals to the vehicles behind in less than 0.1 seconds. This considerably reduced reaction time can make a major contribution towards reducing rear-end collisions such as occur e.g. when encountering traffic jams on motorways. The basis of Highway Pilot Connect is networking between vehicles and precise awareness of the surroundings. Highway Pilot Connect is a further development of the well-tried Highway Pilot system by Daimler Trucks. This system allows trucks to drive semi-autonomously, and has been under test since October 2015, in a standard Mercedes-Benz Actros operating on public roads in Germany. The Highway Pilot was first presented in July 2014, in the Mercedes-Benz Future Truck 2025 study, followed by the very first public road authorization for an autonomously driving truck in May 2015, for the Freightliner Inspiration Truck (earlier post). Compared to the Highway Pilot, Highway Pilot Connect has the additional technical function for electronic vehicle docking. Communication between vehicles is made possible by an onboard telematics platform. A specific V2V (vehicle-to-vehicle) communication module using a special WiFi standard reserved exclusively for automotive enables direct data transfer between the trucks. Highway Pilot Connect uses this for a constant exchange of information with other trucks and the environment. Because of their technology, all the members of such a platoon continue to be autonomously driving trucks. They are able to maintain their direction independently of the vehicle ahead, and thanks to their combination of linear and lateral guidance, they can react to unexpected situations at any time. This also applies if other vehicles cut into or leave the platoon’s space. In this case the vehicle can smoothly disengage from the platoon and continue alone in autonomous mode. The driver does not need to intervene. Docking three or more vehicles together becomes particularly interesting in countries with a corresponding infrastructure. In the USA or Australia, for example, trucks cover long distances without bridges and exit roads on highways crossing the entire continent. Daimler Trucks is participating in the European Truck Platoon Challenge 2016 (EU TPC)—an initiative of the Netherlands during their ongoing EU presidency—with its three Mercedes-Benz Actros Highway Pilot Connect trucks. Within the European Truck Platoon Challenge, six European truck manufacturers will bring platoons of semi-automated trucks to public roads, crossing borders from various European cities in order to reach their final destination of the Port of Rotterdam on 6 April. The overall objective of all OEMs and the Dutch government is to jointly accelerate the introduction of a harmonized, cross-border regulation to optimize efficient road transport in the EU.
Guo Y.,TPC |
Chen X.,TPC |
Wu K.,International Advisory Committee
IEEE Microwave Magazine | Year: 2014
The IEEE Microwave Theory and Techniques Society (MTT-S) International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications (IMWSBio 2013) was held at the Furama Riverfront Hotel, Singapore, 9-11 December 2013. The IMWS-Bio 2013 received a total submission of 170 papers, including invited papers and regular papers from 22 countries and regions. IMWS-Bio 2013 opened with a welcome speech and appreciation to all distinguished guests and attendees by the conference general chair, Prof. Yongxin Guo. Prof. Nitish V. Thakor, NUS, Singapore/Johns Hopkins University, presented paper titled, 'Frontiers of Implantable Neuro Technologies: From Nerve to Brain to Brain Machine Interface'. Prof. Hoi-Jun Yoo, Korea Advanced Institute of Science and Technology, Republic of Korea presented 'WBAN Circuits and Systems'. In addition to the plenary presentations, the technical program was organized in oral and poster sessions.
Bramoulle M.,TPC |
Marret J.-P.,CEA DAM Ile-de-France |
Michalczyk P.,TPC |
De Cervens D.R.,CEA DAM Ile-de-France
PPPS 2001 - Pulsed Power Plasma Science 2001 | Year: 2015
For current large projects to date, the mass production of new raw materials and the corresponding capacitors has not been completely achieved. Meanwhile, the classic products have been improved, especially those based on the metallized all polypropylene film. The properties of this film show a uniform range in terms of breakdown, with few thickness-dependent variations. For extended lifetime and high current values, the dielectric stress is far from the breakdown level of the polypropylene film. The evolution of the metallizationsegmentation is described through the results obtained on three types of design. Conversely, for short capacitor lifetime and moderate currents, the stress can be situated in the breakdown area of the polypropylene film. Therefore, the working conditions must be precisely defined, especially in terms of charging time and hold time. In both cases, the inrush energy in the defect must be limited and controlled in order to avoid any secondary effect. The resistivities of the metallization play a significant role in controlling the high energy density products. The behavior of the galvanic contacts between the reinforced edges of the metallization and the metal spray is strong enough to allow the use of resistivities of several tens of Ohms per square unit. A comparison between resistivities shows that they can be used as a limitation tool in the self-healing process without undue influence on the current crossing properties. The results obtained on large energy units, ranging from 50 to 100 kilojoules, indicate the capacitors are completely safe, with an energy density of more than 2000 joules per liter for the short lifetime products. Some improvements regarding the purity of the resin and the surface treatment could increase the breakdown level to as high as 30%. The corresponding energy density could be increased to 3000 joules per liter. © 2002 IEEE.