ГИДРООБЪЕМНО-МЕХАНИЧЕСКИЕ ТРАНСМИССИИ МОБИЛЬНЫХ МАШИН. РАСЧЕТ КИНЕМАТИЧЕСКИХ И СИЛОВЫХ ПАРАМЕТРОВ

High efficiency, stepless regulation of speed and power increasingly attracts consumers and manufacturers of technological mobile machines, especially agricultural, to use multi-flow transmissions. To date, amongs 80% of the world market of tractor equipment, produced by leading manufacturers, 18% are tractors with hydrostatic-mechanical transmissions. The aim of this work is to develop a methodology for determining the ability to work of hydrostatic-mechanical transmissions possible schemes. From the literature it is known that 12 single-circuit (with one differential) and 288 double-circuit (with two differentials) there can be only the main structural schemes of hydrostatic-mechanical transmissions. To achieve the aim, a method for estimating an ability to work of possible schemes of hydrostatic-mechanical transmissions according to the criterion of continuity of the function of angular velocities of the links from the regulation parameters of hydraulic machines is proposed. To implement the proposed method, a methodology of calculation of kinematic and power parameters by means of appraising and solving equations that describe the interaction between the elements of single-circuit and double-circuit schemes of hydrostatic-mechanical transmissions, is developed. Analytical dependences for determination of points of discontinuity of the second kind of function of angular velocities of links from the regulation parameters and the working volume of hydraulic machines, the gear ratio of planetary gear set of differential, are determined.The calculation algorithm and the software for selection of the inoperative scheme of hydrostatic-mechanical transmissions are developed. For example, by means of calculations and analysis of variants of schemes for wheeled tractor of tractive class 4, the conditions under which the transmission loses ability to work due to exceeding of angular velocities of links their allowable values, were defined. As a result, the method allows excluding from consideration 5 variants of single-circuit schemes and 257 variants from the 576 double-circuit schemes of hydrostatic-mechanical transmissions.Высокий КПД, бесступенчатое регулирование скорости и мощности все более привлекает потребителей и производителей мобильных машин технологического назначения (особенно сельскохозяйственных) к применению многопоточныхтрансмиссий. К настоящему времени из 80% мирового рынка тракторной техники 18% составляют тракторы с гидрообъемно-механическими трансмиссиями (ГОМТ).Целью данной статьи является разработка методики определения работоспособности возможных схем ГОМТ. Так как из литературных источников известно, что только основных структурных схем ГОМТ может быть 12 одноконтурных (один дифференциал) и 288 двухконтурных (два дифференциала). Для этого предложен метод оценки работоспособности возможных схем ГОМТ по критерию непрерывности функции угловых скоростей звеньев от параметров регулирования гидромашин. Для реализации метода разработана методика расчета кинематических и силовыхпараметров составлением и решением уравнений, описывающих взаимодействия компонентов одноконтурных и двухконтурных схем ГОМТ. Установлены аналитические зависимости для определения точек разрыва второго рода функции угловых скоростей звеньев от параметров регулирования, рабочего объема гидромашин, передаточного отношения планетарного ряда дифференциалов.Разработаны алгоритм и программа расчетов выбора неработоспособных схем ГОМТ. На примере расчетов и анализа вариантов схем для колесного трактора тягового класса 4 установлены условия, при которых трансмиссия теряет работоспособность вследствие превышения угловых скоростей звеньев их допустимым значениям. В результате данный метод позволяет исключить из рассмотрения 5 вариантов одноконтурных и 257 из 576 вариантов двухконтурных схем ГОМТ

Search for DCC in 158A GeV Pb+Pb Collisions

A detailed analysis of the phase space distributions of charged particles and photons have been carried out using two independent methods. The results indicate the presence of nonstatistical fluctuations in localized regions of phase space.Comment: Talk at the PANIC99 Conference, June 9-16, 199

Present Status and Future of DCC Analysis

Disoriented Chiral Condensates (DCC) have been predicted to form in high energy heavy ion collisions where the approximate chiral symmetry of QCD has been restored. This leads to large imbalances in the production of charged to neutral pions. Sophisticated analysis methods are being developed to disentangle DCC events out of the large background of events with conventionally produced particles. We present a short review of current analysis methods and future prospects.Comment: 12 pages, 5 figures. Invited talk presented at the 13th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 97), Tsukuba, Japan, 1-5 Dec 199

Central Pb+Pb Collisions at 158 A GeV/c Studied by Pion-Pion Interferometry

Two-particle correlations have been measured for identified negative pions from central 158 AGeV Pb+Pb collisions and fitted radii of about 7 fm in all dimensions have been obtained. A multi-dimensional study of the radii as a function of kT is presented, including a full correction for the resolution effects of the apparatus. The cross term Rout-long of the standard fit in the Longitudinally CoMoving System (LCMS) and the vl parameter of the generalised Yano-Koonin fit are compatible with 0, suggesting that the source undergoes a boost invariant expansion. The shapes of the correlation functions in Qinv and Qspace have been analyzed in detail. They are not Gaussian but better represented by exponentials. As a consequence, fitting Gaussians to these correlation functions may produce different radii depending on the acceptance of the experimental setup used for the measurement.Comment: 13 pages including 10 figure

Search for Disoriented Chiral Condensates in 158 AGeV Pb+Pb Collisions

The restoration of chiral symmetry and its subsequent breaking through a phase transition has been predicted to create regions of Disoriented Chiral Condensates (DCC). This phenomenon has been predicted to cause anomalous fluctuations in the relative production of charged and neutral pions in high-energy hadronic and nuclear collisions. The WA98 experiment has been used to measure charged and photon multiplicities in the central region of 158 AGeV Pb+Pb collisions at the CERN SPS. In a sample of 212646 events, no clear DCC signal can be distinguished. Using a simple DCC model, we have set a 90% C.L. upper limit on the maximum DCC production allowed by the data.Comment: 20 Pages, LaTeX, uses elsart.cls, 8 eps figures included, submitted to Physics Letters

Multiplicity Distributions and Charged-neutral Fluctuations

Results from the multiplicity distributions of inclusive photons and charged particles, scaling of particle multiplicities, event-by-event multiplicity fluctuations, and charged-neutral fluctuations in 158$\cdot A$ GeV Pb+Pb collisions are presented and discussed. A scaling of charged particle multiplicity as $N_{part}^{1.07\pm 0.05}$ and photons as $N_{part}^{1.12\pm 0.03}$ have been observed, indicating violation of naive wounded nucleon model. The analysis of localized charged-neutral fluctuation indicates a model-independent demonstration of non-statistical fluctuations in both charged particles and photons in limited azimuthal regions. However, no correlated charged-neutral fluctuations are observed.Comment: Talk given at the International Symposium on Nuclear Physics (ISNP-2000), Mumbai, India, 18-22 Dec 2000, Proceedings to be published in Pramana, Journal of Physic

Centrality Dependence of Neutral Pion Production in 158 A GeV Pb + Pb Collisions

The production of neutral pions in 158AGeV Pb+Pb collisions has been studied in the WA98 experiment at the CERN SPS. Transverse momentum spectra are studied for the range 0.3 GeV/c < mT-m0 < 4.0 GeV/c. The results for central collisions are compared to various models. The centrality dependence of the neutral pion spectral shape and yield is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with greater than about 30 participating nucleons which is most naturally explained by assuming an equilibrated system.Comment: 5 pages, Latex, including 3 eps figures, submitted to Phys.Rev.Lett; updated pQCD comparison due to new input from the author, updated references, corrected plotting error in figure

Directed Flow in 158 A GeV 208Pb^{208}Pb + 208Pb^{208}Pb Collisions

The directed flow of protons and positive pions have been studied in 158 A GeV Pb + Pb collisions. A directed flow analysis of the rapidity dependence of the average transverse momentum projected onto the reaction plane is presented for semi-central collisions with impact parameters of approximately 8 fm, where the flow effect is largest. The magnitude of the directed flow is found to be significantly smaller than observed at AGS energies and than RQMD model predictions.The directed flow of protons and positive pions have been studied in 158 A GeV Pb + Pb collisions. A directed flow analysis of the rapidity dependence of the average transverse momentum projected onto the reaction plane is presented for semi-central collisions with impact parameters of approximately 8 fm, where the flow effect is largest. The magnitude of the directed flow is found to be significantly smaller than observed at AGS energies and than RQMD model predictions