OBSERVASI PEMANFAATAN SUMBER DAYA IKAN UNGGULAN DAN STRATEGI PENGEMBANGANNYA DI PERAIRAN KABUPATEN BANGKA SELATAN

Kabupaten Bangka Selatan dikelilingi oleh perairan laut yang berada di posisi sentral tiga jalur migrasi ikan (Selat Malaka, Laut Jawa, dan perairan Natuna). Oleh karenanya, berpeluang besar untuk mengembangkan sumber daya ikan yang dimilikinya. Penelitian ini bertujuan menganalisis jenis sumber daya ikan unggulan, trend produksinya, serta merumuskan strategi prioritas pengembangan sumber daya ikan unggulan di perairan Kabupaten Bangka Selatan. Metode yang digunakan adalah metode scoring, model curve estimation, dan metode AHP. Cumi-cumi, udang, kerapu, kakap merah, dan tenggiri terpilih sebagai sumber daya ikan unggulan. Trend produksi cumi-cumi, kakap merah, dan kerapu mengikuti model polinomial, sedangkan untuk udang dan tenggiri masing-masing bersifat logaritmik dan eksponensial. Strategi prioritas pengembangan sumber daya ikan unggulan di perairan Kabupaten Bangka Selatan adalah promosi optimalisasi pemanfaatan sumber daya ikan unggulan (RK= 0,250), introduksi teknologi dan aktivitas kreatif dalam penangkapan ikan (RK= 0,217), dan pengembangan usaha perikanan berbasis potensi wilayah (RK= 0,167).

Single Mathematical Parameter for Evaluation of the Microorganisms’ Growth as the Objective Function in the Optimization by the DOE Techniques

The cultivation of bacteria sets a ground for studying biological processes in many scientific disciplines. The development of the bacterial population is commonly described with three factors that can be used to evaluate culture conditions. However, selecting only one of them for the optimization protocol is rather problematic and may lead to unintended errors. Therefore, we proposed a novel mathematical approach to obtain a single factor that could be used as the objective function to evaluate the whole growth dynamic and support the optimization of the biomass production process. The sigmoidal-shape curve, which is the commonly used function to plot the amount of biomass versus time, was the base for the mathematical analysis. The key process parameters, such as maximal specific growth rate and lag-phase duration were established with the use of mathematical coefficients of the model curve and combined to create the single growth parameter. Moreover, this parameter was used for the exemplary optimization of the cultivation conditions of Klebsiella pneumoniae that was cultured to be further used in the production of lytic bacteriophages. The proposed growth parameter was successfully validated and used to calculate the optimal process temperature of the selected bacterial strain. The obtained results indicated that the proposed mathematical approach could be effortlessly adapted for a precise evaluation of growth curves.

On the use of growth models for forecasting epidemic outbreaks with application to COVID-19 data

The initial phase dynamics of an epidemic without containment measures is commonly well modeled using exponential growth models. However, in the presence of containment measures, the exponential model becomes less appropriate. Under the implementation of an isolation measure for detected infectives, we propose to model epidemic dynamics by fitting a flexible growth model curve to reported positive cases and to infer the overall epidemic dynamics by introducing information on the detection/testing effort and recovery and death rates. The resulting modeling approach is close to the SIQR (Susceptible- Infectious-Quarantined-Recovered) model framework. We focused on predicting the peaks (time and size) in positive cases, actives cases and new infections. We applied the approach to data from the COVID-19 outbreak in Italy. Fits on limited data before the observed peaks illustrate the ability of the flexible growth model to approach the estimates from the whole data.

Transportation Laws for Carbonate and Sulfate Ions in Concrete Based on Compartment Model

Transportation of carbonate and sulfate ions in concrete under the drying-wetting cycle environment is similar to the ingression and elimination of medicine in human body. Given this similarity, such a process is described dynamically using the classic compartment model in pharmacokinetics. The compartment model was applied to predict the content of carbonate and sulfate ions in different regions of concrete. Factors such as water-cement ratio, salt category, carbonate-ion and sulfate-ion attack depth, and drying-wetting cycle were synthetically considered in the compartment model. In conjunction with the prediction value of the compartment model, the experiment data uniformly distributed two sides of the model curve, and the difference is within the accepted range, thus verifying the reliability of the model prediction consequence. The compartment model in this article provides references for predicting the drying-wetting varied cycles and ions attack depth of concrete under carbonate and sulfate ions attack.

Hyperelastic Material Characterization: How the Change in Mooney-Rivlin Parameter Values Effect the Model Curve

Mooney-Rivlin is the most frequently used model from all models used for mechanical characterization of the hyperelestic materials. Simplicity, applicability in a large rage of strains are the key reasons for regular use of this model. However, depending on the number of parameters, the Mooney model can take several forms. While, nine parameter being the highest order noticed, two parameter model is the most commonly found form in the current research domain. Since two parameter model used repetitively, we investigated the effect of incremental change in two material constant values one at a time, on model curve. As Drucker Stability Criterion is governing the extreme values of material parameters, changes in the model curves are discussed related to it. Resultant effects on stress-strain curves due to change in parameter values were examined and physical effect on the characterization is interpreted accordingly.

Calculation and Analysis of Wind Turbine Health Monitoring Indicators Based on the Relationships with SCADA Data

This paper proposes an evaluation index of wind turbine generator operating health based on the relationships with SCADA (Supervisory Control and Data Acquisition) data. First, the relationship among the data from a wind turbine SCADA system is thoroughly analyzed. Then, a time based sliding window model is used to process the SCADA data by the bin method, and a running state model of the wind turbine is established by data fitting. Taking the normal operation state model of the wind turbine as the standard reference and based on the Euclidean distance between the state model curve and the standard model curve, the health index of the wind turbine operation state is proposed. Finally, using SCADA data from two 2 MW direct-drive wind turbines as examples for analysis and discussion, the results show that: (1) health indicators have good stability and sensitivity to wind turbine operating conditions; (2) the width of the data window in the sliding window model must cover all operating conditions of the wind turbine to ensure that the health index depicts the operating state of the wind turbine; (3) the data window width, window increment, and data fitting modeling all affect the health indicators, and thus, the selection of the sliding window model parameters and the data relationship modeling methods should consider the accuracy and real-time performance of the health indicators; and (4) the data acquisition cycle does not affect the health indicators. Once the basic characteristics of the data relations are known, direct data fitting modeling is more efficient than bin preprocessing modeling.

The transmissibility of hepatitis C virus: a modelling study in Xiamen City, China

This study aimed at estimating the transmissibility of hepatitis C. The data for hepatitis C cases were collected in six districts in Xiamen City, China from 2004 to 2018. A population-mixed susceptible-infectious-chronic-recovered (SICR) model was used to fit the data and the parameters of the model were calculated. The basic reproduction number (R0) and the number of newly transmitted cases by a primary case per month (MNI) were adopted to quantitatively assess the transmissibility of hepatitis C virus (HCV). Eleven curve estimation models were employed to predict the trends of R0 and MNI in the city. The SICR model fits the reported HCV data well (P < 0.01). The median R0 of each district in Xiamen is 0.4059. R0 follows the cubic model curve, the compound curve and the power function curve. The median MNI of each district in Xiamen is 0.0020. MNI follows the cubic model curve, the compound curve and the power function curve. The transmissibility of HCV follows a decreasing trend, which reveals that under the current policy for prevention and control, there would be a high feasibility to eliminate the transmission of HCV in the city.

Non-Dispersive Extraction of Ge(IV) from Aqueous Solutions by Cyanex 923: Transport and Modeling Studies

The transport of germanium from an aqueous solution containing oxalic acid was studied using a flat sheet supported liquid membrane (FSSLM) system. Cyanex 923 immobilized in a polytetrafluoroethylene membrane was employed as a carrier. The solution chemistry and related diagrams were applied to study the transport of germanium. The effectual parameters such as oxalic acid, the carrier, and strip reagent concentrations were evaluated in this study. Based on the results, the oxalic acid concentration of 0.075 mol/L and the carrier concentration of 20 %v/v were the condition in which the efficient germanium transport occurred. Among strip reagents tested, NaOH had the best efficiency to transport germanium through the supported liquid membrane system. Furthermore, the permeation model was obtained to calculate the mass transfer resistances. According to the results, the values of 1 and 1345 s/cm were evaluated for &Delta;m and &Delta;f, respectively. The model curve showed that the P value reached a steady state at higher concentrations of the carrier because the viscosity governed the transport phenomenon.

Evaluation of transformation from even-aged to selection forest by means of Gini index

We used the Gini index for evaluation of the 40-year transformation to selection forests in the Training Forest Enterprise Masaryk Forest Křtiny (Czech Republic). The Gini index values for particular forest stands were compared with the reference values derived from the diameter distribution model curve (type E) by Meyer. From a total of sixteen stands which were evaluated in 2013 (the last periodic inventory), only two stands reached the desired diameter structure. Four other stands reached the desired diameter structure at least once during the transformation period. We recommend the application of Gini index for determination of a success rate of even-aged stand transformation to selection forest.

APLIKASI METODE CURVE NUMBER UNTUK MEMPRESENTASIKAN HUBUNGAN CURAH HUJAN DAN ALIRAN PERMUKAAN DI DAS CILIWUNG HULU – JAWA BARAT

Aliran permukaan/limpasan (run off) merupakan salah satu variabel hidrologi yang sangat penting di dalam menunjang kegiatan pengembangan sumber daya air. Metode prediksi yang handal untuk menghitung jumlah dan laju limpasan yang berasal dari permukaan tanah dan bergerak menuju sungai di suatu DAS yang tidak dilengkapi alat ukur (ungaged watershed) adalah suatu pekerjaan yang sangat sulit dan memerlukanwaktu yang banyak. Penelitian ini dilakukan di DAS Ciliwung Hulu, yang merupakan daerah penting dalam kotribusi banjir di Jakarta. Untuk mengetahaui run off yang terjadi, digunakan data curah hujan dan debit Tahun 2007-2009. Sebagai model, untuk mengetahui run off menggunakan peta penggunaan lahan, peta jenis tanah, dan topografi. Peta-peta tersebut diolah dengan menggunakan Arcview, sehingga didapatkannilai CN. Berdasarkan analisis perhitungan, besarnya debit mendekati 50% dari tebal hujan. Kondisi ini mengindikasikan bahwa kondisi DAS Ciliwung Hulu sudah tidak mampu lagi menyerap curah hujan dengan baik. Korelasi antara hasil prediksi run off model yang menggunakan CN dengan perhitungan run off observasi cukup baik. Hal ini menunjukkan bahwa metode Curve Number cukup dapat mepresentaskan hubungancurah hujan dengan aliran permukaan (run off). kata kunci : Run off observasi, run off model, curve number AbstractRun off (surface flow) is one of the most important hydrological variable in supporting the activities of water resources development. A reliable prediction method to calculate the amount and rate of runoff from the land surface caused by the rain that falls in a watershed that is not equipped with measuring devices (un gauge watershed) is a verydifficult job and requires a lot of time. The research was conducted in the watershed Ciliwung Hulu, which is an important area in relation to the incidence of flooding in Jakarta. Curve Number (CN) method can be used to predict the amount of runoff from a watershed. This model required input of rainfall; land cover maps; soil type maps,and topography. The maps are processed using Arc View software, so we get the value of CN. In this study, we used of rainfall and discharge data 2007-2009. Based on the analysis of calculation, known that amount of surface flow approaching 50% of rainfall depth. This condition indicates that the Ciliwung Hulu watershed conditions were not ableand proper to absorb of rainfall. The correlation between the results of run-off prediction models using CN with run-off observation was quite good. This indicated that the Curve Number method could be able to represent the relationship of rainfall with surface flow (run off) and also to predict runoff key words: Run off observation, run-off model, curve number