The Needle Penetration Test for Predicting Coal Strength

The coal strength parameter is used in operations such as the selection and design of mechanical excavators and coal crushing/grinding equipment. However, coring or cutting prismatic specimens from coal for the standard strength tests is difficult, and sometimes not possible. For this reason a method for the indirect determination of coal strength from easy tests would be useful. In this study, the predictability of coal strength from the needle penetration test was investigated. This is a very easy and practical test method. Point load and needle penetration index (NPI) tests were carried out on coal specimens from Cayirhan coalfield in Turkey. The point load indexes were converted to the uniaxial compressive strength (UCS) values by using the general conversion factor. The UCS and NPI values were evaluated using regression analysis. A strong linear relationship was found between the two parameters. The conversion factor for the UCS-NPI ratio is 0.35 for the tested coal samples. It is concluded that the UCS of coal can be predicted from the NPI.WoSScopu

Association rule hiding

Large repositories of data contain sensitive information that must be protected against unauthorized access. The protection of the confidentiality of this information has been a long-term goal for the database security research community and for the government statistical agencies. Recent advances in data mining and machine learning algorithms have increased the disclosure risks that one may encounter when releasing data to outside parties. A key problem, and still not sufficiently investigated, is the need to balance the confidentiality of the disclosed data with the legitimate needs of the data users. Every disclosure limitation method affects, in some way, and modifies true data values and relationships. We investigate confidentiality issues of a broad category of rules, the association rules. In particular, we present three strategies and five algorithms for hiding a group of association rules, which is characterized as sensitive. One rule is characterized as sensitive if its disclosure risk is above a certain privacy threshold. Sometimes, sensitive rules should not be disclosed to the public since, among other things, they may be used for inferring sensitive data, or they may provide business competitors with an advantage. We also perform an evaluation study of the hiding algorithms in order to analyze their time complexity and the impact that they have in the original database

Increasing Turkey's power system flexibility for grid integration of 50% renewable energy share

Secure and reliable operation of power systems with high wind and solar shares requires system flexibility. In this paper, an hourly-based market and grid simulation model is developed to assess security and reliability of a power system with high wind and solar energy share. The model is applied to Turkey as an emerging G20 country that aims to supply its rapidly growing electricity demand from local renewables and lignite as well as nuclear energy. The most ambitious scenario that covers the 2016–2026 period assumes half of all electricity demand is supplied from renewables (30% wind and solar and 20% other resources). This is achieved by ensuring system flexibility through system-friendly location of wind and solar capacity, energy storage, flexible thermal generators, and demand response. Without system flexibility, 3% of renewable power is curtailed and redispatch share required for system security and reliability doubles from current levels. Moreover, additional transmission grid investments are needed. Improving system flexibility ensures secure and reliable operation but increases system costs by 1%–5% with each flexibility option providing different scale benefits, indicating the need for system-wide planning. As gas-based generation declines below 10%, accounting for energy security benefits will be important. On the other hand, coal supply remains around 25% depending on nuclear energy development. At this crossroad, Turkey needs to make its choices to transition to a secure, clean and affordable energy system. The study addresses quantitatively how the flexibility options contribute to such a transition, providing learnings for countries with similar conditions

Transport sector transformation: integrating electric vehicles in Turkey's distribution grids

This study investigates the impacts of integrating electrical vehicles to pilot distribution grids in Turkey to quantify technical concerns and solutions for the year 2030. Different charging loads that discern home, workplace and public charging are considered under two different cases; “home-charging-support” and “public-charging-support.” Random variables describing arrival time of electrical vehicles to the charging stations and associated state of charge at arrival time are modeled with a stochastic approach. Dependencies of electrical vehicle integration capacities of the pilot regions are investigated quantitatively based on several key performance indices. The study also analyzes effects on key performance indicators of demand response by electrical vehicle users, defined as smart charging. Key results show that there is sufficient capacity in the four selected Turkish distribution grids to integrate almost 10% electrical vehicles in the vehicle stock by 2030. Based on the results, priority areas are outlined for stakeholders including energy policymakers