This paper presents a new approach using Witness Simulation in combating issues related to maintenance within the existing manufacturing facility. Currently, maintenance is a key issue as many machines breakdown due to every day wear and tear as well as the age of the machine itself. This causes bottlenecks within the entire production system as the schedules of production is disturbed and further backlogs are developed. Also, when machines breakdown there seems to be very little communication from one end to another ie parts are needed for the repair of many of the machines, for example, it is very common for the rotary kiln to come to a halt due to increased temperature and different quantities of a mixture of materials. In order to fix the problem and move back on schedule the maintenance team uses certain materials ie same materials, all the time. However, due to not having an adequate stock control system and the lack of communication many a times, parts are not readily available and hence the team wait further until parts arrive at the facility. This paper will demonstrate how all of the above problem areas can be adhered to via the use of adopting a simple automated response system using Witness Simulation. The demonstration will be based on a single machine for testing purposes to ensure efficiency that can later be applied to the entire system as a whole.

This paper explores the use of Bayesian network modeling of machine breakdowns within a cement manufacturing plant. The Bayesian network modeling is introduced using Hugin software and then implemented into a Witness Simulation model using historical data, expert knowledge and opinions. The models simulate 3 parameters of the machine based on life consumption and usage of each parameter, the developed Witness model produces a probability failure rate based on these parameter usages. The failure probability developed by Witness is implemented using the Chain Rule; this is compared with the probability for failure based on the Bayesian network model. This enables the user to see the probability of failure developed by the implementation of the chain rule and Witness based on the parameter usage, on a live streaming fashion as the model is running. This can be used as a decision making tool for management to consider machine maintenance affectively based on parameter usage.

This paper explores the value of stochastic simulation as a tool for predicting current or future reliability of machinery, it helps to understand machine failures by using confidence levels developed through replications and exploring the changes that occur. A stochastic simulation model has been constructed representing a crusher machine with in a cement manufacturing plant. The crusher machine has three parameters; namely those are drill head, dusting and lubrication. The consumption of these parameters results in the development of a probability of failure for the machine using Bayes theory.

ABSTRACT

This study reviews the Public Transportation (PT) Systems and the opportunities and requirements applied

in Libya. Beginning with the definition of public transport systems and their functions and areas of applied and

advanced systems for public transport and advanced systems for traffic management, systems and operations of

transport vehicles and advanced systems to control private vehicle and safety, with a discussion of the

importance of each of them, this paper discusses the requirements of the application of Bus Rapid Transit

(BRT) systems in mass with focus placed on the importance of developing an outline plan for the public

transport systems. The concept master plan and the options available in Tripoli shall be discussed to develop its

map of structural public transportation systems and recommend consideration of the possible adoption of a map

structure developed in the advanced countries and some developing countries in this area, with their adaptations

depending on the circumstances of Tripoli. It also concludes with the need to establish a permanent institution

representing the parties involved, including the public sectors, academia; and vested in the institutions

responsible for managing, directing, and the preparation of a strategic plan for public transport systems,

including the development of the master plan for those systems. The study recommends starting with pilot

projects carefully selected by an explanatory expansion in the application.

Key words: public transport system, bus rapid transit, safety, control private vehicles, traffic management,

Tripoli.

ABSTRACT

This study reviews the Public Transportation (PT) Systems and the opportunities and requirements applied

in Libya. Beginning with the definition of public transport systems and their functions and areas of applied and

advanced systems for public transport and advanced systems for traffic management, systems and operations of

transport vehicles and advanced systems to control private vehicle and safety, with a discussion of the

importance of each of them, this paper discusses the requirements of the application of Bus Rapid Transit

(BRT) systems in mass with focus placed on the importance of developing an outline plan for the public

transport systems. The concept master plan and the options available in Tripoli shall be discussed to develop its

map of structural public transportation systems and recommend consideration of the possible adoption of a map

structure developed in the advanced countries and some developing countries in this area, with their adaptations

depending on the circumstances of Tripoli. It also concludes with the need to establish a permanent institution

representing the parties involved, including the public sectors, academia; and vested in the institutions

responsible for managing, directing, and the preparation of a strategic plan for public transport systems,

including the development of the master plan for those systems. The study recommends starting with pilot

projects carefully selected by an explanatory expansion in the application.

Key words: public transport system, bus rapid transit, safety, control private vehicles, traffic management,

Tripoli

The higher strength 7xxx aluminum alloys exhibited low resistance to stress corrosion cracking (SCC) when aged to the peak hardness (T6 temper). The overaged alloys (T7 temper) developed to enhance the SCC with loss in the strength of the alloy. Recently, retrogression and re-aging (RRA) heat treatments are used for improving the SCC behavior for alloys in T6 tempers such as 7075, 7475 and 8090. In this study, an application of retrogression and re-aging heat treatment processes are carried out to enhance toughness properties of the 7079-T651 aluminum alloy, while maintaining the higher strength of T651-temper. The results of charpy impact energy and electrical conductivity tests show a significantly increases in absorbed energy and electrical conductivity values, when the alloys are exposed to various retrogression temperatures (190, 200, 210°C) and times (20, 40, 60 minutes), and then re-aged at 160°C for 18 hours.

ABSTRACT

Increasing the private vehicles namely own car, taxi, microbuses and coaches as

a mode of transport is due to its inherent advantages associated with its usage. In

Tripoli due to rapid increase in private vehicles usage associated with no public

transport system namely public buses and train has resulted in increase of traffic

congestion problem, accidents and inadequate of parking spaces. The objective of

this study which identify the factors encourage users of own car and private

vehicles to shifting to public transport system. Re-establish of public transport

system and decreasing own car users simultaneously has become necessary for

solving traffic congestion problems and reduces road accidents and travel time

for all trips. A questionnaire survey was carried out on users of private vehicles

transport in the Tripoli such as car owners, passengers, taxis and microbuses

drivers (n = 900). The probability of car drivers shifting to public transport was

examined based on scenario several options such as reduction and improve in

public transport travel time. Improve travel time by70% will be encourage

switching about 82.3% to switch from use own car to use public transport system

services. Logistic regression technique has been used to analyses the factor that

impact users to switch their trips to public transportation system alternatives.

Statistical Package for Social Science (SPSS) version 19 and Excel 2007

software were used to analysis the questionnaire in this study.

.

Keyword: Improve travel time, reduction traffic congestion, public transport,

road safety

Abstract: Currently, Tripoli the capital city of Libya experiences a steady increase in traffic

volumes on its road network especially in the city centre. The increase has caused traffic

problems. Tripoli has registered an increase private cars ownership approaching 743,796

vehicles of the total registered vehicles in the city, which reach more than one million at the

end of 2009. A study has been carried out in Tripoli city authority areas among own car users

who live in the areas with lack of private transport and no public transport (PT) services. A

questionnaire survey in Tripoli area was carried out to study the potential reduction of private

cars on road through optimal use of suitable public transportation system in order to reduce

traffic problems and travel time. Logistic regression model has been used to analyse the factor

that impacts users to switch their trips to public transportation alternatives.

Key Words: own car, private transport, travel time, logistic regression

Abstract: Increasing dominance of private car as a mode of transport is due to its inherent advantages

associated with its usage. In Tripoli, Libya due to rapid increase in car usage associated with poor

public transport system, has resulted in increase of traffic congestion, road accidents and street parking

spaces. This study aims to identify the factors encourage users of own car to switching to public

transport. Introducing the public transport (PT) system and reduce own car users simultaneously has

become necessary for solving congestion problems and reduces road accidents and improve travel time

for all trips. A questionnaire survey was carried out on users of transport in the city such as car

owners, passengers, taxis and micro buses drivers (n = 600). The probability of car drivers switching

to public transport was examined based on scenario several options such as reduce and improve in

public transport travel time. Logistic regression technique has been used to analyses the factor that

impact users to switch their trips to public transportation alternatives. Statistical Package for Social

Science (SPSS) and Excel 2007 software were used to analysis the questionnaire in this study.

Key words: Travel time, traffic congestion, public transport, road safety, logistic regression technique

Abstract— Transport modes are very important to Libyan’s Tripoli residents for their daily trips. However, the total number of own car and private transport namely taxi and micro buses on the road increases and causes many problems such as traffic congestion, accidents, air and noise pollution. These problems then causes other related phenomena to the travel activities such as delay in trips, stress and frustration to motorists which may affect their productivity and efficiency to both workers and students. Delay may also increase travel cost as well inefficiency in trips making if compare to other public transport users in some Arabs cities. Switching to public transport (PT) modes alternatives such as buses, light rail transit and underground train could improve travel time and travel costs. A transport study has been carried out at Tripoli City Authority areas among own car users who live in areas with inadequate of private transport and poor public transportation services. Analyses about relation between factors such as travel time, travel cost, trip purpose and parking cost have been made to answer research questions. Logistic regression technique has been used to analyse these factors that influence users to switch their trips mode to public transport alternatives.

Keywords --- Own car, private transport, public transport, parking cost, logistic regression.