Quantitative Assessment on Navigation Impact of the Controlled Waterway in the Upper Yangtze River Using Queuing Model

As an important transportation link between eastern and western economic zones of China, the Yangtze River waterway has been globally ranked first in relation to freight volume since 2010, and the density of ship traffic has also increased significantly. However, the inland navigation system has been increasingly threatened by traffic congestion, which is more serious in the controlled waterways of the upper Yangtze River. In this study, the distribution laws of ship traffic flow and service time in the controlled waterway were analyzed, indicating that the traffic flow obeys the Poisson distribution, and the service time obeys a negative exponential distribution. Thereafter, by simplifying the queuing processes and rules, the M/M/1 queuing service model was established to calculate ship queuing indicators in a controlled waterway. It was found that the ship queuing indicators varied greatly among different controlled waterways. Compared with downstream ships, upstream ships usually had longer queuing lengths and times, which were also more affected by the increasing number of ship arrivals and service times. Consequently, a dimensionless loss coefficient was proposed to quantify the influence of the controlled waterway on the navigation capacity. As the service time and number of ships increased, the loss coefficient also increased. The results of this study could provide references for understanding the ship queuing problem, and thereby the assessment of navigation capacity and anchorage constructions in a controlled waterway.

Daily Precipitation Concentration in Central Coast Vietnam

Empirical frequency distribution of daily precipitation amounts can be fitted by a negative exponential distribution, because anywhere there are many small daily totals and few large ones. Therefore, the cumulative percentages of days with precipitation, sorted in increasing order according to their amounts, against the cumulative percentage of the rainfall amounts that they contribute are fitted by positive exponential curves Y = aX, a and b constants. Based on these curves, the Concentration Index (CI) evaluates the contribution of the rainiest days to the total amount. In this study the CI has been calculated for 15 meteorological stations in Da Nang city and Quang Nam province in Central Coast Vietnam, for the 1979–2016 period. The results show high values of CI, ranging from 0.62 to 0.72. Conversely, the linear correlation between altitude and CI is negative (R=-0.60, p < 0.01). There are no correlations between the latitude nor the annual mean number of precipitation days and the CI. CI change for the sub-periods of 1979–1997 and 1998–2016 is also analyzed.

Reliability and Sensitivity Analysis of a Repairable System with Warranty and Administrative Delay in Repair

The purpose of this study is to analyze the behavior of some industrial systems in light of the cost-free warranty policy. According to this policy, we assume that the repairman is not always present in the system. When the active unit fails, the repairman will be called to visit the system; however, administrative procedures may delay the visit for some time. Once on the system, the repairman first inspects whether the fault is caused by the user or not and whether it is repairable or not. According to product warranty laws, the repairman carries out the repair or replacement of the faulty unit. The failure time, administrative delay time, inspection time, and repair time are assumed taken as a negative exponential distribution. The system model is analyzed by the supplementary variable technique and Laplace transform, as various performance metrics of system efficiency have been obtained. The sensitivity and relative sensitivity analyses for the system parameters have also been performed. Finally, an illustrative example is taken to illustrate the efficiency of the system.

CARGO OPTIMIZATION IN AN AIRLINE USING AGENT – BASED MODELLING

Cargo plays a very important role in the aviation industry as a supporting revenue. In Airline X, cargo supports the revenue by 4% - 6% of the total revenue. There are opportunities to optimize the cargo compartment in Airline X by analyzing every agent involved in the purpose to know the optimum cargo loaded into the compartment using Agent-Based Modelling. The method used in this research is Rejection Sampling in Monte Carlo and Agent-Based Modelling. In addition, the theory used in this research is distribution function, to determine what type of distribution that represents the agent behavior. The final result shows that with the predetermined number of iterations, which is 300 iterations, the optimal value was obtained base on the convergent result. On the other hand, the distribution of passenger and baggage described as the Gaussian Distribution Function, while the distribution of EBT described as the Negative Exponential Distribution Function. These distributions represent agent behavior.

Profit Analysis of a Standby Repairable System with Priority to Preventive Maintenance and Rest of Server Between Repairs

The paper aims to bring out the profit analysis of a system with cold standby redundancy of two identical units. In the system, we keep one unit productive and the other is to backup the operation. The system requires preventive maintenance after a specific time. In addition to that, the server is allowed to rest between two consecutive repairs. The repairs are done to increase the efficiency and productivity level of the system. The repair and rest times follow arbitrary distributions while the random variable related to failure time of the unit follows negative exponential distribution. The provision of priority has been made for the preventive maintenance over repairs. Some important reliability characteristics are studied in steady state by using the approach of stochastic processes. The revenue per unit time and the cost per unit time for which server is busy in repairs and maintenances are considered for determining the profit incurred to the system. The results are shown graphically and numerically to highlight the effect of different parameters on some significant reliability characteristics.

Tripod Turnstile Machines Performance Analysis for the System Safety and Security without Considering Simultaneous Failures using Reliability Approach

As the crime is increasing day by day around the world. To stop the crime many security gadgets and machines have been developed by various security agencies. The tripod turnstile machine also helps in stopping the crime and restricting the entry of unauthorized person on the premises. In this paper, the aim is to analyze the reliability measures of the two tripod turnstile machines which work in a parallel configuration. In the case of non-functionality of the machine, unauthorized persons may enter into the premises. Due to security and safety reason, organizations install these machines. Hence these machines must be highly reliable in the operation to avoid any unwanted event. In this paper, for the considered system, the transition state diagram has been drawn with the help of the Markov model. The Chapman-Kolmogorov differential equations are developed from the transition state diagram and solved using Laplace transformation. The failure and repair rates are assumed to be constant and follow negative exponential distribution. The system upstate and downstate probabilities are determined. The explicit expression of the system Availability, Reliability and MTTF are also obtained. The sensitivity analysis is also performed to determine which machine affects the system reliability the most.

Stochastic Analysis of a Computer System with Unit Wise Cold Standby Redundancy and Failure of Service Facility

Here, we analyze stochastically a computer system by taking one more similar unit (called computer system) in cold standby redundancy. The computer system consists of hardware and software components together. The provision of a single service facility has been made for repairing hardware and up-grading the software. The failure of the service facility is considered which resumes the jobs with full efficiency as new after availing treatment. The failure rates of hardware and software components as well as failure rate of the service facility are taken as constant and thus follow negative exponential distribution. The treatment rate of the service facility, repair rate of the hardware and up-gradation rate of the software follow arbitrary distributions with different probability density functions. Efforts have been made to determine reliability measures in steady state by using SMP and RPT. The behavior of MTSF, availability and also the profit function is observed graphically for some particular situations of the parameters.

Statistical Behaviour of Time Occurrences and Magnitude of Aftershock Sequences

&lt;p&gt;The negative exponential distribution of the magnitude (that is the well-known Gutenberg-Richter relation) and the negative exponential distribution of interarrival times constitute the backbone of the seismic hazard analysis.&lt;/p&gt;&lt;p&gt;Our goal is to check if these two distributions could be considered an acceptable model also for aftershock sequences.&lt;/p&gt;&lt;p&gt;We analysed several aftershock sequences, with mainshocks ranging from &lt;em&gt;M=5.45&amp;#160; &lt;/em&gt;to &lt;em&gt;M=7.3&lt;/em&gt;; six sequences of Californian earthquakes selected from the SCEC database and an Italian sequence, selected from INGV-CNT Catalog.&lt;/p&gt;&lt;p&gt;The results show that the G-R relation fits remarkably the data, with a &lt;em&gt;&amp;#946;&lt;/em&gt; value ranging from &lt;em&gt;-1.8&amp;#160;&lt;/em&gt; to &lt;em&gt;-2.4&lt;/em&gt;. The temporal behaviour shows an acceptable fit to the negative exponential distribution:&amp;#160; all the sequences exhibit a good fit for &lt;em&gt;&amp;#916;t&gt;2.5 hours&lt;/em&gt;, on the contrary for &lt;em&gt;&amp;#916;t&lt;2.5 hours&lt;/em&gt; Weibull distribution is more suitable.&lt;/p&gt;

Strong convergence of multivariate maxima

It is well known and readily seen that the maximum of n independent and uniformly on [0, 1] distributed random variables, suitably standardised, converges in total variation distance, as n increases, to the standard negative exponential distribution. We extend this result to higher dimensions by considering copulas. We show that the strong convergence result holds for copulas that are in a differential neighbourhood of a multivariate generalised Pareto copula. Sklar’s theorem then implies convergence in variational distance of the maximum of n independent and identically distributed random vectors with arbitrary common distribution function and (under conditions on the marginals) of its appropriately normalised version. We illustrate how these convergence results can be exploited to establish the almost-sure consistency of some estimation procedures for max-stable models, using sample maxima.

Analysis of signal quality in FSO systems with PolSK modulation

In this paper, the quality of the Polarization Shift Keying (PolSK) modulated signal in a Free Space Optical (FSO) system is analyzed. The atmospheric channel is statistically modeled with four different distributions, namely, the Gamma-Gamma distribution, Negative Exponential distribution, Kdistribution, and I-K distribution. For all four channel models, the Average Bit Error Rate (ABER) at the receiving side of the system is determined in an analytically closed form. The results are graphically presented and discussed in order to determine the impact of certain parameters on the ABER, i.e., the quality of the received signal in the PolSK modulated FSO system. These parameters are the Signal-to-Noise Ratio (SNR), the FSO link distance, the wavelength at which the signal is transmitted, and the atmospheric turbulence strength.