Evaluation and optimization of disc grating machine for sago starch production (Metroxylon spp.).

The production of Sago starch involving multiple processes and the grating process was the most important since the recovery of sago starch was directly affected. In order to produce a finer size of grated sago and high starch recovery, a new design of sago disc grating machine has been developed. A evaluation was performed to determine the optimum operation on the basis of the feeding rate and grating speed input on the sago disc grating machine, and the starch recovery as the output. The grated sago was dried and sieved at different sizes to analysis the size. A model equation was developed to predict the starch recovery. As the result, the optimum feeding rate was 0.1 m/min with 1500 rpm of grating speed produce 23.57% of sago starch recovery. Studies show that the feeding rate and grating speed affects the size of the grated sago produced (P<0.01) and directly affects starch recovery.

On the 5G Communications: Fractal-Shaped Antennas for PPDR Applications

In this study, one method of using antennas based on fractals to cover few kinds of public protection and disaster relief (PPDR) communications was presented. Dedicated antenna forms, necessary for antenna design by 5G implementation, were enhanced to suit the requirements of specific applications. Employing fractal-shaped antennas have allowed us to accomplish all these actions, which request compact, conformal, and broadband high performance devices. Antennas derived from Koch’s curve fractals are studied. In order to implement PPDR communications in 5G technology, frequency bandwidths of importance have been carefully selected and properly included in the antenna developments under MATLAB environment. Important information necessary for antenna designers, such as 360 degrees directivity at various frequencies, the impedance (resistance and reactance) along the bandwidth of interest, as well as voltage standing wave ratio (VSWR) along the bandwidth of interest for dipole, one-iteration, and two-iteration Koch’s curves, respectively, have been obtained. The characteristic of directivity at selected frequencies is also highlighted. In order to maximize antenna parameters, this study has successfully proposed using fractal antennas, objects that use self-similarity property of fractals for optimum operation in several frequency ranges. For the studied antennas, we have obtained the following results regarding the maximum gains in dBi (which is the unit of the ratio between the gains of the antenna compared to the gain of an isotropic antenna). For the dipole antennas, the gains are 2.73 dBi and 4.76 dBi at 460 MHz and 770 MHz, respectively. The gains for one-iteration fractal Koch antenna are 6.91 dBi and 4.51 dBi at 460 MHz and 770 MHz, respectively, and finally, for two-iteration fractal Koch antenna, the gains are 4.91 dBi and 3.28 dBi at 460 MHz and 770 MHz, respectively. Moreover, the impedance along the bandwidth is approximately 360 Ohms for two-iteration fractal Koch antenna, 180 Ohms for one-iteration fractal Koch antenna, and 140 Ohms for dipole antenna, respectively.

NECESSITY OF PRESERVATION OF THE NATURAL CLIMATE OF TSKHALTUBO (KUMISTAVI) CAVE DURING ITS OPERATION

To preserve the natural climate regime in the Tskhaltubo Cave Systems it is necessary to carry out the permanent seasonal meteorological observations on the climatic parameters in the underground area. Which will ensure the optimum operation of the cave system. By means of mentioned conditions will be to the conservation and this facility. For preservation of the natural regime of air circulation and for preservation of the optimum climate parameters, we consider it is necessary to introduce the following restrictions: during the cold period, the number of visitors should not exceed 7,000 person/season, and. in summer and spring — 2000-2700 person relatively. It is necessary to establish a special research laboratory. During the operation of the cave, the following activities should be carried out systematically: monitoring the inside environment microclimate: obtaining data on ionization and radioactivity of the air. on gas and bacteriological compositions of the air. on changes in the levels of underground waters according to diurnal and seasonal cycles and the attention should be paid to the prevention of pollution.

NECESSITY OF PRESERVATION OF THE NATURAL CLIMATE OF TSKHALTUBO (KUMISTAVI) CAVE DURING ITS OPERATION

To preserve the natural climate regime in the Tskhaltubo Cave Systems it is necessary to carry out the permanent seasonal meteorological observations on the climatic parameters in the underground area. Which will ensure the optimum operation of the cave system. By means of mentioned conditions will be to the conservation and this facility. For preservation of the natural regime of air circulation and for preservation of the optimum climate parameters, we consider it is necessary to introduce the following restrictions: during the cold period, the number of visitors should not exceed 7,000 person/season, and. in summer and spring — 2000-2700 person relatively. It is necessary to establish a special research laboratory. During the operation of the cave, the following activities should be carried out systematically: monitoring the inside environment microclimate: obtaining data on ionization and radioactivity of the air. on gas and bacteriological compositions of the air. on changes in the levels of underground waters according to diurnal and seasonal cycles and the attention should be paid to the prevention of pollution.

Simulative and analytical methods of bidirectional EDFA amplifiers in optical communication links in the optimum case

This study has demonstrated the simulative and analytical methods of bidirectional EDFA amplifiers in optical communication links in the optimum case. The output power, max. Q factor and light signal/noise ratio variations are clarified with pump power variations at the bidirectional amplification EDFA amplifier for the previous/proposed models at optimum EDFA length of 8 m. As well as the output power and max. Q factor variations with EDFA amplifier length variations are demonstrated at the bidirectional amplification EDFA amplifier for the previous/proposed models at various pump power levels. The optimum operation efficiency case is observed at 8 m EDFA amplifier length and 120 mW pumping power.