Strength properties of xanthan gum and guar gum treated kaolin at different water contents

Nowadays, using biopolymer as a ground improvement method has become very popular. However,since biopolymers are organic and degradable, their long-term effect is not fully known. In this study, the effects of biopolymers on the mechanical behavior of kaolin clay were investigated through a comprehensive program of experiments. Two types of biopolymer, i.e. xanthan gum and guar gum were chosen to investigate the effect of biopolymer type. For this purpose, specimens were prepared using standard Proctor energy at four different water contents(25%, 30% 35% and 40%) with 0.5%, 1%, 1.5% and 2%biopolymer inclusions. The specimens were cured for 1 d, 7 d, 28 d and 90 d. Moreover, some of the specimens were kept in the curing room for 3 years to observe the long-term effect of the biopolymers.At the end of the curing periods, the specimens were subjected to unconfined compression test, and scanning electron microscopy(SEM) analysis was performed to observe the mechanism of strength improvement. The results revealed that the unconfined compressive strength(UCS) of the specimens treated with biopolymers increased in all biopolymer inclusion levels and water contents up to a 90-d curing period. For specimens containing xanthan gum, the maximum strength increase was observed at 25% water content and 2% xanthan gum with 90-d curing. The strength increased 5.23 times induced by xanthan gum addition when compared to the pure clay. Moreover, the increase in strength reached 8.53 times in specimens treated with guar gum. Besides, increasing water content caused more ductile behavior, thus increasing the axial deformation.     

Isolation and characterization of verocytotoxin-producing Escherichia coli O157 from Turkish cattle

The objective of this study was to collect rectal swabs from the cattle in a slaughterhouse located in Hatay (Turkey) immediately after slaughter for the isolation and characterization of verotoxin-producing Escherichia coli O157 in each month during a 1-year period. The rectal swab samples were analyzed for the isolation of E. coli O157 through pre-enrichment, immunomagnetic separation and selective plating on CT-SMAC agar. E. coli O157 was isolated from 77 (13.6%) of the samples. The presence of E. coli O157 changed during a 1-year period, in that the occurrence of E. coli O157 was the highest in July and November and lowest in February. A total of 66 isolates out of 77 were serotype O157:H7 and 11 were serotype O157:NM. PCR analysis of E. coli O157 virulence genes revealed that all O157:H7/NM were positive for rbf(O157), 74 positive for EhlyA, 72 positive for eaeA, 62 positive for vtx2, and 3 positive for both vtx1 and vtx2. It was presented by cytotoxicity tests that many of E. coli O157 isolates showed high cytotoxicity on Vero cells. All of the isolates containing EhlyA showed enterohaemolysin production.     

Solution approaches for a real-life resource-constrained parallel machine scheduling problem

This paper deals with a real-world scheduling problem in an injection-molding department of an electrical appliance plant. In the department, a resource-constrained parallel machine scheduling problem with machine eligibility restrictions is investigated. First, an integer-programming (IP) model with the objective of minimizing makespan is developed for the entire problem. Since this entire IP model has a huge number of variables, it cannot handle the problem efficiently. To obtain more efficient results, two solution approaches, namely IP/IP and IP/constraint programming (CP) both of which partition the entire problem into loading and scheduling sub-problems, are proposed. The loading phase, in which an IP loading model assigns the jobs to machines with the aim of minimizing maximum load on the machines and operators, is the same for both approaches. Subsequently, in the scheduling phase, the IP/IP approach uses an IP scheduling model while the IP/CP approach applies a CP scheduling model to obtain the final schedule of the jobs. Computational results show that the proposed solution methods improve makespan values for almost all test problems in comparison to the entire IP model. In particular, the IP/IP approach performs better in the test problems with greater number of operators, whereas IP/CP approach provides quick and practical results in almost all test problems and gives relatively more efficient makespan values when the resource constraints are tight (i.e., the case of smaller number of operators).     

Common cause failure analysis of cyber–physical systems situated in constructed environments

While cyber–physical system sciences are developing methods for studying reliability that span domains such as mechanics, electronics and control, there remains a lack of methods for investigating the impact of the environment on the system. External conditions such as flooding, fire or toxic gas may damage equipment and failing to foresee such possibilities will result in invalid worst-case estimates of the safety and reliability of the system. Even if single component failures are anticipated, abnormal environmental conditions may result in common cause failures that cripple the system. This paper proposes a framework for modeling interactions between a cyber–physical system and its environment. The framework is limited to environments consisting of spaces with clear physical boundaries, such as power plants, buildings, mines and urban underground infrastructures. The purpose of the framework is to support simulation-based risk analysis of an initiating event such as an equipment failure or flooding. The functional failure identification and propagation (FFIP) framework is extended for this purpose, so that the simulation is able to detect component failures arising from abnormal environmental conditions and vice versa: Flooding could be caused by a failure in a pipe or valve component. As abnormal flow states propagate through the system and its environment, the goal of the simulation is to identify the system-wide cumulative effect of the initiating event and any related common cause failure scenario. FFIP determines this effect in terms of degradation or loss of the functionality of the system. The method is demonstrated with a nuclear reactor’s redundant coolant supply system.     

Selection and implementation of pollution prevention techniques in small and medium enterprises in countries in transition

This paper aims to open the discussion about the possibility and economic feasibility of applying pollution prevention techniques in industrial enterprises with smaller production capacities than those specified in Directive 2010/75/EU. The work refers to countries with transition economies where low cost of environmental resources and pollution fees are present. The research is conducted on pilot sample of seven small- and medium-size enterprises belonging to the food and beverage sector. The enterprises have different characteristics in terms of company size, capacity levels, production processes employed, and status of the transition in terms of their ownership status. The selection of appropriate prevention techniques is done using newly developed Method for Identification of Prevention Techniques (“MIP”). The MIP method combines: (i) Minimization Opportunities Environmental Diagnosis methodology developed by Regional Activity Center for Sustainable Consumption and Production Barcelona and its approach to data collection, (ii) United Nation Industrial Development Organisation’s step-by-step approach to environmental diagnosis of industrial enterprises, (iii) Driving Forces, Pressure, State, Impact, Response Framework used by European Environmental Agency to facilitate problem–solution identification, (iv) Multicriteria ranking method for selection of best available techniques, and (v) Philosophy of Shewhart–Deming’s circle to introduce the system of planning, control, and correction and integrate prevention concept into business policy. This provided necessary flexibility corresponding to companies’ abilities to finance implementation. The results confirmed that the pollution prevention concept can be applied to small- and medium-sized companies of different production capacities and organization levels with both environmental and economic benefits.     

Promoting risk communication in early design through linguistic analyses

The concept of function offers significant potential for transforming thinking and reasoning about engineering design as well as providing a common thread for relating together product risk information. This paper focuses specifically on risk data by examining how this information is addressed for a design team conducting early stage design for space missions. A fundamental set of risk elements is proposed based on a linguistic analysis of the risk information needs of the design team. Sample risk statements are then decomposed into a set of key attributes that are used to scrutinize the risk information using three approaches from the pragmatics sub-field of linguistics: (1) Gricean, (2) Relevance Theory, and (3) Functional Analysis. Based on the deficiencies identified in this analysis, a format for the communication of risk data by explicitly accounting for five risk attributes developed in this work is formulated.     

Demographic/socio-economic factors and dietary habits determining consumer exposure to foodborne bacterial hazards in Turkey through the consumption of meat

Meat is considered a major source of foodborne bacterial pathogens. Assessing the risks for public health of meat consumption is achieved by “Risk Analysis”- a concept firmly established on a global level - so as to ensure the level of consumer protection as stipulated by international trade agreements. Risk analysis identifies and characterizes potential hazards, which allows estimating the associated risks, provided reliable data on consumer exposure are available. The latter varies by geographical region and associated differences in culture and socio-economic position of the consumer. This paper is dedicated to assessing the exposure of the Turkish population to bacterial hazards resulting from consumption of typical traditional meat dishes. It reviews current data on meat consumption in different regions of Turkey, on the basis of which seven typical preparations and consumption scenarios are identified. Major demographic and socio-economic differences along Turkey`s east–west axis were identified, such as the degree of urbanization, consumers’ age, household size, preferred meat animal species, frequency and volumes of meat consumption, and preparation techniques. Considering all these variables allowed a differentiated and reliable assessment of consumers’ exposure to biological hazards. This information is essential for greater accuracy in estimating the public health risks associated with various meat-borne hazards in this country.     

Goal Programming Model Subsystem of a Flexible Nurse Scheduling Support System

A model for nurse scheduling via the goal programming versions of the traditional “set covering” model is discussed in detail. The demand profile and nurses preferences are fed into an expert like capability designed to formulate a goal programming representation of the problem. Solutions to the goal programmed model are made available for various goal priority options. Each solution can be disaggregated into specific assignments for specific units and nurses.     

An integrated multicriteria decision-making methodology for outsourcing management

In this study, an outsourcer evaluation and management system is developed for a textile company by use of fuzzy goal programming (FGP). At first phase of the methodology, evaluation criteria for the outsourcers and the objectives of the company are determined. The existing outsourcers of the company are evaluated by PROMETHEE. At the second phase, the FGP model developed selects the most appropriate outsourcers suitable to be strategic partners with the company and simultaneously allocates the quantities to be ordered to them. In the end, the results achieved are compared with the current situation of the company. The results indicated that scientific methodology for outsourcer management system is very beneficial for the company.Scope and purposeThe purchasing activities of a company constitute a very important part in the overall operation of the company. The quality and the delivery capabilities of any manufacturing firm depend heavily on the performance of its suppliers. When companies outsource a significant part of their business and become more dependent on outsourcers, the quality and delivery performance of the company depends totally on its outsourcers. The consequences of poor decision making become more severe. It is therefore too important for an outsourcing type manufacturer to evaluate, manage and select their suppliers. This research proposes an outsourcer evaluation and management system on scientific basis. The procedure developed is made up of two phases. The first one is the evaluation of outsourcers in terms of the decision maker's objectives. This phase is followed by FGP modeling phase which provides the decision maker the list of suitable outsourcers.