Irrigation Management in GAP

The multisectoral Southeastern Anatolia Project (GAP) is the largest regional developmentplan for one of the less developed parts of Turkey. The GAP project includes the irrigation of 1.7 million ha of land and generation of 27 billion kWh of hydroelectric power with an installed capacity of 7500 MW. In order to optimize the benefits to be obtained from irrigation and to ensure sustainable irrigation in the GAP area, the Government of Turkey has commissioned the GAP Management, and Operation Maintenance study (GAP MOM). The overall MOM model provides an institutional and organizational framework that promotes the most effective development of irrigated agriculture in the GAP region. This goal can be expressed as three major objectives: maximize net benefits, ensure sustainability and be implementable and flexible.     

Guest Editor's Introduction

Minds and Machines -     

Floc settling characteristics of turbid water coagulated with moringa oleifera seeds

The results of studies into the particle aggregations and settling rates of flocs from turbid water (kaolin suspension) with turbidities varying from 50 to 550 NTU coagulated with Moringa oleifera seeds are presented. The results of the laboratory based study showed that the maximum value of the “apparent aggregation rate”, K _app,increased with increase in initial turbidity. K _app was found to be 0.000778 for low turbidity (50 NTU) and 0.00654 for high turbidity (550 NTU). The velocity gradient for rapid mix at the maximum K _app was found to be constant at 443/sec for all turbidities. Settling rate of floc coagulated with Moringa oleifera seed was dependent on the initial turbidity of the water sample. For water with initial turbidity of 50 NTU, 30% to 70% turbidity was removed between 60 and 210 minutes, while for high turbidity of 400 to 550 NTU, 80% to 95% turbidity removal occurred between 60 and 150 minutes.     

Bench Scale Studies for Pretreatment of Sanitary Landfill Leachate with Moringa Oleifera Seeds Extract

A laboratory study using a bench scale model of two unit operations involved processes of coagulation (using Moringa oleifera seeds as a natural coagulant) and flocculation-sedimentation have been adopted to treat the leachate from Air Hitam Sanitary Landfill at Puchong in Malaysia. The results of this study has shown, that M. oleifera has a potential for the removal of heavy metals from the leachate, and may be used as a pre-treatment stage for biological treatment to eliminate a portion of the toxic heavy metals, which limit the activity of micro-organisms in the leachate.     

DESIGN OF PIC-CONTROLLED PULSED ULTRASONIC TRANSMITTER FOR MEASURING GINGIVA THICKNESS

The aim of this study is to design and implement a noninvasive ultrasonic thickness measurement device that determines the gingiva thickness, which is quite an important criterion in dentistry, by using A-mode ultrasonic method. Operating frequency of the device is selected as 8 MHz, since gingival thickness is quite slight. The measurements are performed as 192.5 μm precision by the implemented system. Surface-mounted devices integrated circuits (SMD ICs) and electronic parts are used in the implementation of the device. Thus, a small-dimension, handheld device has been design and constructed. The transmitter of the device is tested under simulated object, and encouraging results were obtained.     

Supercritical carbon dioxide extraction of spearmint oil from mint-plant leaves

Spearmint oil (essential oil of Mentha spicata) was extracted from Turkish mint-plant leaves using supercritical CO₂ in a basket-type extractor. Effects of temperature, pressure, extraction time, amount of CO₂, and entrainer (ethanol) concentration on composition of essential-oil extracts and oil yield, relative to hydro-distillation, were investigated. Relative yields were as high as 80%. Monoterpenes fraction in extracts was inversely correlated with relative oil yields. Monoterpenes were preferentially extracted by CO₂ due to their high vapor pressure, low molar mass and low polarity. Supercritical extraction presented advantages over the conventional hydro-distillation by yielding extracts lower in monoterpenes fraction and by enabling high yields at temperatures safe for the heat-sensitive essential oil.     

Control and dynamic analysis of a packed distillation column based on modeling approaches

In this work, dynamic analysis and control of a packed distillation column have been utilized theoretically and experimentally. In theoretical studies, two types of mathematical models stagewise (Frank model) and partial differential approaches (back-mixing model), were used. Packed distillation uses 1400 mm packing height, and packing type is rashing ring with 20-15 mm diameter. The reboiler was made from a 13 L glass container. Reflux ratio was adjusted by an on-line computer. The system temperature was measured with six thermocouples. For control studies, the reflux ratio and the reboiler heat dutywere chosen as manipulated variables. Perturbation in feed composition was utilized as the disturbance. Decoupling multivariable dynamic matrix control (DDMC) and Nondecoupling multivariable dynamic matrix control (NDMC) of overhead and bottom compositions were applied for control studies. Performance of the control system was tested by using an integral absolute error (IAE) criterion and it was also compared with decoupling multivariable PID control (DPID) and Nondecoupling multivariable PID control (NDPID).     

Determination of the Optimum NiS Fire Assay Parameters for Pt,Pd, and Rh in Automotive Exhaust Catalytic Converters

This work investigates the performance of the nickel sulfide fire assay (NiS-FA) for the pyrometallurgical analysis of platinum group elements (PGEs) from mixtures of automotive exhaust catalytic converters (e.g., gasoline, diesel, and diesel particular filter) by assessing the effects of various flux materials and reaction parameters on platinum, palladium, and rhodium recovery. Inductively coupled plasma mass spectrometry and atomic absorption spectroscopy (AAS) are used for the analysis of the NiS-FA beads. We found that the optimum recovery (at least 99.0%) was achieved with reaction of 11.5 g of flux (0.53 w/w ratio, sodium tetraborate:sodium carbonate), 1 g nickel, and 0.84 g sulfur (1.2 w/w ratio, Ni:S) per gram of sample for 90 min at 975°C. Reference standards (NIST SRM 2557) were used to compare efficiencies and identify the optimum conditions. The results are consistent with certified values and PGEs could be recovered within the 95% confidence level. The precision (<4.0% RSD) of all measurements, expressed as percentage relative standard deviation (SD), ranged up to 3.0%.     

Thermodynamic analysis of an existing coal-fired power plant for district heating/cooling application

In a conventional coal-fired power plant, which is only designed for electricity generation, 2/3 of fuel energy is wasted through stack gases and cooling water of condensers. This waste energy could be recovered by trigeneration; modifying the plants in order to meet district heating/cooling demand of their locations. In this paper, thermodynamical analysis of trigeneration conversion of a public coal-fired power plant, which is designed only for electricity generation, has been carried out. Waste heat potentials and other heat extraction capabilities have been evaluated. Best effective steam extraction point for district heating/cooling system; have been identified by conducting energetic and exergetic performance analyses. Analyses results revealed that the low-pressure turbine inlet stage is the most convenient point for steam extraction for the plant analyzed.