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.     

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.     

Numerical Determination of Thermal-Diffusivity Coefficients of Some Nematic Liquid Crystals <Emphasis Type="Italic">in Situ</Emphasis>

In this study, a new experimental study has been implemented to determine the thermal-diffusivity parameters of industrial nematic liquid crystals, 4-pentyl-4′-cyanobiphenyl (5CB) and 4′-octyl-4-cyanobiphenyl (8CB), both numerically by using the finite difference method (FDM) for forward solutions and experimentally by measuring the temperature variation with time and position. The most important parts of this experimental study are the heating system and the liquid crystal cell, which were constructed in-house to determine the temperatures of the materials in situ. Four different positions for local measurements have been studied, and the optimum graph of this variation has been determined. The experimental and theoretical results of this study are consistent with previous measurements performed by means of a conventional thermal technique.     

An introduction to the special issue section on “The 7th International Conference on Photosynthesis and Hydrogen Energy Production in Honor of Nathan Nelson and T. Nejat Veziroğlu, 19–25 June 2016, Pushchino,Russia”

The research in photosynthesis and hydrogen energy production provides a unique opportunity for transforming sustainable solar energy into our energy system. This special issue presented the selected and invited papers from the International Conference on Photosynthesis Research for Sustainability in honor of Nathan Nelson and T. Nejat Veziro?lu which was held on June 19–25, 2016, in Pushchino, Russia. These papers offered readers with some of the most recent and exciting progresses in photosynthesis and hydrogen energy production. The potential limitations and future efforts with open questions were also offered to stimulate the further research endeavors in the field.     

Measurement of mass attenuation coefficients,effective atomic numbers,and electron densities for different parts of medicinal aromatic plants in low-energy region

The mass attenuation coefficients(l/q) for different parts(root, flower, stem, and leaf) of three medicinal aromatic plants(Teucrium chamaedrys L. subsp. sinuatum,Rheum ribes, and Chrysophthalmum montanum) were measured using an ~(241)Am photon source in a stable geometry and calculated using the Monte Carlo N-Particle Transport Code System-extended(MCNPX) code and the WinXCOM program. The experimental and theoretical MCNPX and WinXCOM values exhibited good agreement.The measured mass attenuation coefficient values were then used to compute the effective atomic number(Z_(eff))and electron density(N_E) of the samples. The results reveal that S1-S(stem of Teucrium chamaedrys L. subsp. sinuatum) has the highest values of l/q and Zeff.     

Effects of thermo‐fatigue loading,hydrostatic pressure,and heat aging on the free‐volume and crystalline structure of polypropylene‐co‐ethylene random copolymer pipes

Plastic pipes composed of polypropylene‐co‐ethylene random copolymers were subjected to accelerated aging by thermo‐fatigue loading (i.e., thermal cycling using hot and cold water alternately under pressure), application of hydrostatic pressure at elevated temperatures, and heat aging in an oven. The effects of these accelerated aging techniques on the molecular and crystalline structure of the material were investigated using positron annihilation lifetime spectroscopy, Fourier‐transform infrared spectroscopy, and differential scanning calorimetry. It was found that all three types of applied aging techniques decreased the size of the defects in the crystalline–amorphous interphase of the material, increased the density of these defects, and had a negligible impact on the free‐volume hole size and intensity of the amorphous phase. Thermo‐fatigue loading resulted in decreased lamellae thickness and lamellae thickness distribution; in contrast, hydrostatic pressure loading resulted in increased lamellae thickness and lamellae thickness distribution. The effect of thermo‐fatigue loading on the chemical degradation of polypropylene was more pronounced than the effects of hydrostatic pressure and heat aging. POLYM. ENG. SCI., 55:641–650, 2015. © 2014 Society of Plastics Engineers