Законы распределения некоторых параметров при организации движения поездов

We consider the planning problem for freight transportation between two railroad stations. We are required to fulfill orders (transport cars by trains) that arrive at arbitrary time moments and have different value (weight). The speed of trains moving between stations may be different. We consider problem settings with both fixed and undefined departure times for the trains. For the problem with fixed train departure times we propose an algorithm for minimizing the weighted lateness of orders with time complexity O(qn 2 log n) operations, where q is the number of trains and n is the number of orders. For the problem with undefined train departure and arrival times we construct a Pareto optimal set of schedules optimal with respect to criteria wL max and C max in O(n 2 max{n log n, q log v}) operations, where v is the number of time windows during which the trains can depart. The proposed algorithm allows to minimize both weighted lateness wL max and total time of fulfilling freight delivery orders C max.

The study reveals an influence of the main technological parameters on the probability of failing and uptime work to receive and dispatch transit cargo trains in time. The determined regularities concern failures resulting from changes in the daily load, the technological equipment of transit depots, and uneven sizes of arriving and departing flows of trains. The importance of the research is grounded on a lack of objective assessment of the reliability of a standard operational model of processes that take place at maintenance depots for railway transport, which means that it is essential to determine the probability of failure of timely receipt and dispatch of cargo trains. The level of failure and the trouble-free uptime are mainly affected by the size of the operational fleet of train locomotives, the uneven number of daily trains, and the minimal pre-set intervals of associated arrivals and departures of trains. The research has established that the existing standards ensure the required level of reliability (the probability of a timely acceptance of trains at 95 %). However, the time of trains’ staying on receiving and departure tracks exceeds the norm almost 4 times, which minimizes the likelihood of timely departures of trains. The probability of failure in timely departures is not taken into account by the current regulations; therefore, it is suggested that such a standard should be introduced. The undertaken tests facilitate objective evaluation of the reliability of the typical technological processes that take place at technical railway stations and entail the need to review the methods of its rationing.

Uncertainty about possible train delays has an impact on train trips, as the exact arrival time is unknown during trip planning. Delays can lead to missing a connecting train at the transfer station, or to coming too late to an appointment at the destination. Facing this uncertainty, the traveler may wish to use an earlier train or a different connection arriving well before the appointment. Currently, train trip planning is based on scheduled times of connections between two stations. Information about approximate delays is only available shortly before train departure. Although several visualization approaches can show temporal uncertainty, we are not aware of any visual design specifically supporting trip planning, which can show delay uncertainty and its impact on the connections. We propose and evaluate a visual design which extends train trip planning with delay uncertainty. It shows the scheduled train connections together with their expected train delays as well as their impacts on both the arrival time, and the potential of missing a transfer. The visualization also includes information about alternative connections in case of these critical transfers. In this way the user is able to judge which train connection is suitable for a trip. We conducted a user study with 76 participants to evaluate our design. We compared it to two alternative presentations that are prominent in Germany. The study showed that our design performs comparably well for tasks concerning train schedules. The additional uncertainty display as well as the visualization of alternative connections was appreciated and well understood. The participants were able to estimate when they would likely arrive at their destination despite possible train delays while they were unable to estimate this with existing presentations. The users would prefer to use the new design for their trip planning.

This paper describes how, given the complexity and number of constraints to be taken into account, train timetabling is a difficult and time-consuming task. A feasible train timetable should specify the departure and arrival time of each train to each location of its journey so that the line capacity and other operational constraints are met. Traditionally, train timetables have been generated manually by drawing trains on the time-distance diagram, where train schedules are manually adjusted so that all constraints are fulfilled. This process can take a long time and it usually stops once a feasible timetable is found. The difficulty of the process increases in complex and high-loaded networks and the resulting timetabling may be far from optimal. This paper presents MOM: a friendly, flexible, computer-based Decision Support System (DSS) whose main goal is to support the railway planner to efficiently obtain optimized train timetables. The system generates feasible and high quality timetables by considering the set of constraints of the problem and optimization criteria related to the use of railway infrastructures and operator requirements. The railway planner can obtain several solutions automatically, by modifying certain parameters (departure interval, frequencies, among others). Hence, the user can analyze them and take decisions about conditions related to railway traffic and infrastructure. Furthermore, an important feature of the DSS is the consideration of hard and soft constraints which makes the search process more flexible and reaches better solutions. The developed DSS offers assistance in train scheduling, conclusions about the maximum capacity of the network, identifying bottlenecks, determining the consequences of changes, providing support in the resolution of incidents, and alternative planning in on-line scheduling for real traffic control. This DSS software is being successfully used by the Spanish Manager of Railway Infrastructure (ADIF).

A new method is proposed for single-track railway freight train timetable with two-stage solution of train scheduling problem. The method describes train scheduling problem in matrix with the "signaling block" concept. The matrix represents entire block occupancy of trains between inter-stations and internal-stations while decomposing individual train occupancy, making optimization method more flexible in design and use. The "two-stage solution" refers to that of train timetable with "conflict solution" and "timetable optimization." At the beginning, related data for trains are entered to build the initial timetable, which is then transferred and saved as the matrix format. All conflicts between interstations and internal-stations are located; solutions are made with manual scheduling to generate a feasible timetable. In the second stage, departure and stop time of freight trains, and passenger trains if necessary, are adjusted with Fuzzy system. Before optimization, storage is made in ascending amount of extra-time percent in freight train schedule. Execution is made subject to pre-ordered results during optimization for computer program acceleration of current manual spotting solution to find reasonable and feasible solution. The two-stage method also takes less time than the regular railway timetable design methods in cost saving of manual labor and providing higher operation performance and efficiency.

Responses were recorded extra- or intracellularly from single, small afferent fibers of the goldfish saccule, that is, S2 fibers, to clarify how the spontaneous and sound-evoked firings in these fibers are initiated from generator potentials. Spontaneously active units randomly selected from the saccular nerve of five goldfish (total 78 units) were classified by the coefficient of variation (CV) of interspike intervals into irregular (59 units; CV greater than 0.3), intermediate (10 units), and regular types (9 units; CV less than 0.23). The irregular type showed a burst (38 units) or random (21 units) pattern of firing in spontaneous activity. In cases where a clear generator potential could be recorded in response to each sound wave, spontaneous generator potentials could also be observed in the absence of stimulus sound. These spontaneous potentials were irregular in amplitude and time course, and often contained components much slower than the sound-evoked generator potentials. The sound-evoked generator potentials in S2 fibers were produced with a delay of 0.4-0.85 ms following each sound wave, and had a time course comparable to the sound-evoked excitatory postsynaptic potentials (EPSPs) of large S1 fibers. They also shared other properties such as adaptive decline in amplitude, incremental and decremental responses, and off-suppression. The mean amplitude of the sound-evoked generator potentials in S2 fibers was linearly related to the rate of afferent firing. There was no apparent difference in the action potential threshold amplitude for spontaneous and sound-evoked generator potentials. It may be concluded that the generator potentials that underlie the spontaneous and sound-evoked firing of S2 fibers are produced by the release of transmitter by hair cells.

Objective To explore the heart rate variability (HRV) of dynamic electrocardiogram in children with benign or malignant ventricular premature beat (VPB) and healthy children, and analyze the changes of time and frequency domain indexes of HRV. Methods From January 2012 to December 2017, a total of 100 children with VPB diagnosed by auxiliary examinations and follow-up visits results, who were 6-14 years old and accepted dynamic electrocardiogram test in West China Second University Hospital, Sichuan University were recruited in this study. According to benign or malignant VPB, they were divided into benign VPB group (n=50) and malignant VPB group (n=50). Children in malignant VPB group were all combined with organic heart diseases, such as congenital heart defects (4 cases), dilated cardiomyopathy (DCM) (9 cases ), and viral myocarditis (37 cases) diagnosed by abnormal myocardial enzyme levels. Meanwhile, 50 cases of healthy children with the same age range who received dynamic electrocardiogram in the same hospital during the same period and the results were normal were included into control group. Measurement data with normal distribution and homogeneity such as standard deviation of all normal-to-normal intervals (SDNN), standard deviation of average normal-to-normal intervals (SDANN), root mean square of the successive difference (rMSSD), percentage normal-to-normal interval deviation greater than 50 ms (PNN50), coefficient of variance (CV), coefficient of variance (ULF), very-low frequencies (VLF), low frequencies (LF), and high frequencies (HF) were expressed by ±s. And those data among 3 groups were compared by one-way ANOVA, further comparisons between each two groups were conducted by least singnificant difference (LSD) test. Numeration data such as constituent ratio of genders were expressed by rate (%), and were compared by chi-square test among 3 groups. There were no significant differences among 3 groups in the constituent ratio of gender and age (P>0.05). This study met the requirements of the World Medical Association Declaration of Helsinki revised in 2013. Clinical informed consent was obtained from each child′s guardians. Results There were significant differences among 3 groups in HRV analysis results of time domain indicators such as SDNN, SDANN, rMSSD, PNN50, CV, and frequency domain indicators such as ULF, VLF, LF and HF (F=42.304, 14.144, 26.344, 15.362, 8.115, 18.031, 10.611, 20.928, 13.719; P 0.05), and PNN50 and HF between benign VPB group and control group (P>0.05), but there were significant differences in the others time domain indicators and frequency domain indicators of HRV between each two groups (P<0.05). Conclusions The HRV analysis of dynamic electrocardiogram is helpful in determining benign and malignant VPB in children. However, prospective randomized controlled trials with multicenter and large-sample size are needed to evaluate whether the HRV analysis can be used to determine the severity of VPB and as a prognosis marker in children with VPB. Key words: Arrhythmias, cardiac; Ventricular premature complexes; Heart rate variability; Electrocardiography; Controlled clinical trial; Child

With the rapid development of China’s social economy and the improvement of people’s living standards, people’s travel demand grows rapidly. As high-speed rail provides fast and comfortable services, the number of high-speed railway passengers is increasing exponentially. During the holidays, huge numbers of railway passengers always bring great pressure and challenge to the transport companies, particularly at large railway stations. Accurately forecasting passengers’ travel demand during holidays is of practical significance to efficiently develop train schedules, formulate effective emergency plans and early warning schemes and guarantee the operating safety. With historical passenger flow data of Beijing West Railway Station during the Spring Festival, we analyse and forecast the future passenger flow using a trend analysis method. The result provides suggestions on organization optimization and improvement for Beijing West Railway Station, which can be used by other railway passenger stations as references.

The spontaneous activity and the response to intrastriatal application of apomorphine of substantia nigra pars reticulata (SNpr) single units was studied in four experimental groups of rats: (1) normal rats; (2) subthalamic nucleus (STN) lesioned rats; (3) rats bearing a 6-hydroxydopamine (60HDA) lesion; and (4) 60HDA-lesioned animals with an additional STN lesion. Thirty-eight percent of units from 60HDA-lesioned rats showed a bursting pattern of spontaneous activity, which was never found in normal rats. STN lesions had no effect on the spontaneous activity of SNpr units from normal rats, but reduced the percentage of burst units in 60HDA-lesioned animals. Intrastriatal apomorphine produced responses in 62% of SNpr units from normal rats and 85% of units from 60HDA-lesioned animals (P < 0.05). In addition, the modifications in the firing rate and in the coefficient of variation of the interspike intervals induced by intrastriatal apomorphine were significantly greater for the units isolated from 60HDA-lesioned rats. In particular, it was noted that all the burst units responded to apomorphine, showing the highest changes in firing rate and coefficient of variation. However, intrastriatal apomorphine did not always turn the activity of burst units into a more physiological pattern. STN lesions reduced the percentage of units responding to intrastriatal apomorphine in normal rats. In 60HDA-lesioned rats, STN lesions reduced the number of responsive units, and their change in mean firing rate and coefficient of variation. Our results show that the STN participates in the genesis of the bursting pattern of activity of SNpr units in 60HDA-lesioned rats, and that STN lesions can partially revert the abnormal spontaneous and apomorphine-induced responses of SNpr units in these animals.

To delineate quantitatively differences in suck‐swallow‐ respiration coordination during feeding in term infants exposed to drugs in utero, 16 control infants (10 females, six males; mean birthweight 3209g, standard error of the mean [SEM] 103g) and 15 drug‐exposed infants (seven females, eight males; seven cocaine, eight opiates; neonatal abstinence [Finnegan] scores less than 10; mean birthweight 3001g, SEM 93g) were studied in the first three days of life and again at one month of age. Coefficients of variation (COVs) of suck‐suck, swallow‐swallow, and breath‐breath intervals were used as measures of stability of individual rhythms. COVs of suck‐swallow and swallow‐breath intervals were used to determine stability of multiply integrated rhythms. In the first three days of life, a significantly higher percentage of‘apneic swallows’(runs of three or more swallows not associated with breathing movements, divided by total run‐swallows) was noted during feeding in the drug‐exposed infants (mean 5.3% SEM 1.7%) compared with controls (mean 0.9%, SEM 0.4%; p&lt;0.02), who also had less breath‐breath rhythmic stability (higher COV) and shorter swallow‐breath intervals. These differences were no longer evident at one month of age. Opiate‐exposed infants were generally more affected than the cocaine‐exposed infants. Swallowing was less rhythmic in the drug‐exposed cohort, especially in opiate‐exposed infants, but this difference also disappeared by one month. In the first days of life, drug‐exposed infants were less efficient feeders, ingesting less volume per run‐swallow than controls (mean 0.31ml, SEM 0.05ml, versus 0.45ml, SEM 0.05ml; p&lt;0.05). The decreased efficiency appeared to be compensated for by a slightly faster swallow rate (mean 53 swallows per minute SEM 2 versus 47 swallows per min, SEM 1, in controls; p&lt;0.005). By one month of age these differences between groups had disappeared as well. Intrauterine drug exposure, even in infants with relatively mild symptoms of withdrawal, may adversely impact development of brainstem respiratory and swallow centers, thus affecting, albeit transiently, the underlying biorhythms of feeding.

Busy, complex railway stations that serve as origin and termination points for a significant proportion of trains are essential to regional railway networks. Resolving conflicts between arrival–departure operations and shunting operations of cross-line trains and originating or terminating passenger trains in the throat area is important for safety in these multidirectional stations. The main task of this paper is to study the train platforming problem, and we consider the integration of track and route allocation with shunting route allocation on the basis of the traditional TTP problem, so as to formulate a strong anti-interference track allocation plan for busy, complex railway stations. Therefore, in view of the complex characteristics of train operation in busy, complex railway stations, we extensively examine the technical operational characteristics of various trains in multidirectional stations, which are the key constraints of the model, and establish a mixed-integer linear programming model. This model aims to balance the buffer time for track occupation and optimize the routing and scheduling of trains in stations. Furthermore, an improved genetic algorithm is proposed to effectively implement the developed model. In the case study of Guangzhou Station, the occupation analysis after the optimization of the method in this paper indicates that the shunting operations significantly interfere with arrival–departure operations in throat areas. The optimization of buffer times and track utilization times resulted in notable reductions of 30.55% and 77.82%, respectively, in quadratic differences. These outcomes provide empirical evidence supporting the feasibility of the proposed model and algorithm for addressing train platforming problems, particularly in complex, multidirectional, and heavily trafficked railway stations.

Tentative Characterization of Old Structural Concrete through Mechanical Fracture Parameters

Energy consumption for multiple trains on the urban subway line is predominantly affected by the operation strategy. This paper proposed an energy-saving operation strategy for multiple trains, which is suitable for various line conditions and complex train schedules. The model and operation modes of the strategy are illustrated in detail, aiming to take full use of regenerative braking energy in complex multi-train systems with different departure intervals and dwell times. The computing method is proposed by means of the heuristic algorithm to obtain the optimum operation curve for each train. The simulation result based on a real urban subway line is provided to verify the correctness and effectiveness of the proposed energy-saving operation strategy.

This paper aims to investigate the ultimate lateral capacity of suction caissons embedded in clay with spatially varying undrained shear strength in the framework of probabilistic analysis for the first time. A non-stationary three-dimensional random field is used to represent the undrained shear strength with a linearly increasing trend with depths below the mudline. The stochastic finite difference method is employed to determine the probabilistic ultimate lateral capacity of suction caissons. The influences of the clay undrained strength heterogeneity κ, the coefficient of variation of undrained strength COVsu, and the autocorrelation distances on the probability density function (PDF) curves and cumulative distribution function (CDF) curves of the normalized ultimate lateral capacity N h are investigated . It is found that both the mean and standard deviation of normalized ultimate lateral capacity N h increase with the undrained strength heterogeneity κ, but the coefficient of variation of N h does not. Besides, the small autocorrelation distance of clay results in the low variability of normalized ultimate lateral capacity. This indicates the significance of probabilistic site characterization of the undrained strength of clay.

According to the forecast target indicators values of the JSC “Russian Railways” integrated development project until 2023, it is necessary to increase the East Siberian railway capacity of the mountain-pass section of the Bolshoy Lug – Slyudyanka-II up to 137 pairs of trains per day. The freight trains number should be 107 pairs per day, a raft of pushing locomotives in the odd direction up to 19 units. The section transportation capacity will increase to 116.7 million tons per year. According to the specified operation parameters, with the growth of cargo turnover on the Irkutsk – Slyudyanka section by 2023, the available capacity shortage will be 14 pairs of trains. In freight traffic, if all provided reserve lines of the the regulatory schedule are used, the capacity deficit will be 11 pairs of various categories trains. The article offers a solution of the existing section power supply devices strengthening problem until the inter-train interval of 8 minutes is reached, for this purpose, the technical parameters of the section substations are considered, and the performance indicators that can provide reliable and cost-effective working conditions are determined. The operation conditions of a traction power network (TPN) of the Bolshoy Lug – Slyudyanka-II section under the existing traffic schedule and under the prospective train schedule are compared. Traction calculations have a special role, since they serve as the basis for drawing up optimal train schedules, determining the railway lines capacity, effectively placing separate points, traction substations, fuel depots, determining the locomotives electricity and fuel consumption rate, solving other practical problems. Traction operation calculation of the electrified mountain pass section of the Bolshoy Lug – Slyudyanka-II railway line was performed using the KORTES software package. The power supply parameters of a given section were used as input data: the separate points number and location, the current speed limits for trains on this section, the longitudinal profile of the railway track, the categories and types of trains that pass through the section, the trains weights and the electric rolling stock types used in the calculation.