The perception of stakeholders on regional transformation on the outskirts of Yogyakarta City,Indonesia

The research was conducted on the outskirts of Yogyakarta City that administratively include three districts of Sleman Regency, namely Depok, Gamping, and Mlati, and three districts of Bantul Regency, namely Kasihan, Sewon, and Banguntapan. It aimed to obtain a deeper understanding on the perceptions of stakeholders on the regional transformation phenomena occurring on the outskirts of Yogyakarta City. This is a qualitative case study research with a single case. The case study research method was selected because the observed phenomenon is contemporary and the analyzed issue is unique. It used a qualitative method with field observations and in-depth interviews to several informants as data acquisition techniques. The informants were stakeholders from state/government, private sector/entrepreneur, academics, and civil society, which were selected using purposive sampling method. The research data processing and analysis included: (1) data reduction, (2) data presentation, and (3) data conclusion. In order to examine the reliability and validity of the data, the research used source triangulation method. The results showed that all stakeholders perceived the regional transformation on the outskirts of Yogyakarta City to have positive and negative consequences on various dimensions. The positive ones were the economic opportunities, generated by the regional transformation process, for both the native people and the migrants. Aside from these positive consequences, the regional transformation on the outskirts of Yogyakarta City also caused negative impacts on the physical, economic, social, and cultural dimensions of the outskirts.     

Characteristics of VHF radiowave scintillations over a solar cycle (1983–1993) at a low-latitude station: Waltair (17.7°N, 83.3°E)

The characteristics of VHF radiowave scintillations at 244 MHz (FLEETSAT) during a complete solar cycle (1983–93) at a low-latitude station, Waltair (17.7°N, 83.3°E), are presented. The occurrence of night-time scintillations shows equinoctial maxima and summer minima in all the epochs of solar activity, and follows the solar activity. The daytime scintillation occurrence is negatively correlated with the solar activity and shows maximum occurrence during the summer months in a period of low solar activity. The occurrence of night-time scintillations is inhibited during disturbed days of high solar activity and enhanced during low solar activity.     

Robust inversion of vertical electrical sounding data using a multiple reweighted least-squares method

The root cause of the instability problem of the least-squares (LS) solution of the resistivity inverse problem is the ill-conditioning of the sensitivity matrix. To circumvent this problem a new LS approach has been investigated in this paper. At each iteration, the sensitivity matrix is weighted in multiple ways generating a set of systems of linear equations. By solving each system, several candidate models are obtained. As a consequence, the space of models is explored in a more extensive and effective way resulting in a more robust and stable LS approach to solving the resistivity inverse problem. This new approach is called the multiple reweighted LS method (MRLS). The problems encountered when using the L ₁- or L ₂-norm are discussed and the advantages of working with the MRLS method are highlighted. A five-layer earth model which generates an ill-conditioned matrix due to equivalence is used to generate a synthetic data set for the Schlumberger configuration. The data are randomly corrupted by noise and then inverted by using L ₂, L ₁ and the MRLS algorithm. The stabilized solutions, even though blurred, could only be obtained by using a heavy ridge regression parameter in L ₂- and L ₁-norms. On the other hand, the MRLS solution is stable without regression factors and is superior and clearer. For a better appraisal the same initial model was used in all cases. The MRLS algorithm is also demonstrated for a field data set: a stable solution is obtained.     

Fast automatic solution of the inverse resistivity problem

The paper presents a fast automatic approach to solve the inverse resistivity problem, assisted by optimization, which is a non-linear model-fitting technique. The selected inverse problems are ill-posed and the inverse solution is defined by ‘best fit’ in the sense of least-squares. Formulations are presented in a systematic manner for Newton’s method, least squares method and Marquardt’s modification (ridge regression) method based on local linearization of non-linear problem. The convergence of least-squares method and Marquardt’s method, to provide a robust solution, are first tested on a theoretical model and effectiveness of Marquardt’s method is demonstrated, and then two-field apparent resistivity curves from Banda district, India are interpreted and discussed.     

An evaluation of force-based design vs. direct displacement-based design of jointed precast post-tensioned wall systems

The unique features of jointed post-tensioned wall systems, which include minimum structural damage and re-centering capability when subjected to earthquake lateral loads, are the result of using unbonded post-tensioning to attach the walls to the foundation, along with employing energy dissipating shear connectors between the walls. Using acceptance criteria defined in terms of inter-story drift, residual drift, and floor acceleration, this study presents a multiplelevel performance-based seismic evaluation of two five-story unbonded post-tensioned jointed precast wall systems. The design and analysis of these two wall systems, established as the direct displacement-based and force-based solutions for a prototype building used in the PREcast Seismic Structural Systems （PRESSS） program, were performed at 60% scale so that the analysis model could be validated using the PRESSS test data. Both buildings satisfied the performance criteria at four levels of earthquake motions although the design base shear of the direct displacement-based jointed wall system was 50% of that demanded by the force-based design method. The study also investigated the feasibility of controlling the maximum transient inter-story drift in a jointed wall system by increasing the number of energy dissipating shear connectors between the walls but without significantly affecting its re-centering capability.     

Remote sensing for landscape parameters and scale effect

Journal of the Indian Society of Remote Sensing - Development activities must be compatible for possibilities and limitation of natural environment and resources. Predevelopmental analysis must...     

A 10-year wave energy resource assessment and trends of Indonesia based on satellite observations

Wave energy resource assessment and trends around Indonesian's ocean has been carried out by means of analyzing satellite observations. Wave energy flux or wave power can be approximated using parameterized sea states derived from satellite data. Unfortunately, only some surface parameters can be measured from remote sensing satellites, for example for ocean surface waves: significant wave height. Others, like peak wave period and energy period are not available, but can instead be estimated using empirical models. The results have been assessed by meteorological season. The assessment shows clearly where and when the wave power resource is promising around Indonesian's ocean. The most striking result was found from June to August, in which about 30–40 kW/m(the 90 th percentile: 40–60 kW/m, the 99th percentile: 50–70 kW/m) wave power energy on average has been found around south of the Java Island. The significant trends of wave energy at the 95% level have also been studied and it is found that the trends only occurred for the extreme cases, which is the 99th percentile(i.e.,highest 1%). Wave power energy could increase up to 150 W/m per year. The significant wave heights and wave power have been compared with the results obtained from global wave model hindcast carried out by wave model WAVEWATCH III. The comparisons indicated excellent agreements.     

Double-difference tomography of P- and S-wave velocity structure beneath the western part of Java,Indonesia

West Java in the western part of the Sunda Arc has a relatively high seismicity due to subduction activity and faults. In this study, double-difference tomography was used to obtain the 3D velocity tomograms of P and S waves beneath the western part of Java. To infer the geometry of the structure beneath the study area, precise earthquake hypocenter determination was first performed before tomographic imaging. For this, earthquake waveform data were extracted from the regional Meteorological, Climatological, Geophysical Agency (BMKG) network of Indonesia from South Sumatra to Central Java. The P and S arrival times for about 1,000 events in the period April 2009 to July 2016 were selected, the key features being events of magnitude > 3, azimuthal gap < 210° and number of phases > 8. A nonlinear method using the oct-tree sampling algorithm from the NonLinLoc program was employed to determine the earthquake hypocenters. The hypocenter locations were then relocated using double-difference tomography (tomoDD). A significant reduction of travel-time (root mean square basis) and a better clustering of earthquakes were achieved which correlated well with the geological structure in West Java. Double-difference tomography was found to give a clear velocity structure, especially beneath the volcanic arc area, i.e., under Mt Anak Krakatau, Mt Salak and the mountains complex in the southern part of West Java. Low velocity anomalies for the P and S waves as well as the v_P/v_S ratio below the volcanoes indicated possible partial melting of the upper mantle which ascended from the subducted slab beneath the volcanic arc.     

CFD simulation and experimental analysis of flow dynamics and grinding performance of opposed fluidized bed air jet mill

This paper presents a three dimensional Computational Fluid Dynamics (CFD) model to investigate the flow dynamics of solid–gas phases during fine grinding in an air jet mill. Alpine 100AFG fluidized bed air jet mill is considered for the study and the jet milling model is simulated using FLUENT 6.3.2 using a standard k-ε model. The model is developed in GAMBIT 2.3.16 and meshed by tet/hybrid (T-Grid) and Triangular (Pave) meshes. The effects of operating parameters such as solid feed rate, grinding air pressure and internal classifier speed on the performance of the jet mill are analyzed. The CFD simulation results are presented in the forms of dual phase vector plot, volume fraction of phases and particle trajectories during fine grinding process. The mass of ground feed entering and leaving the cyclone (underflow) is also computed by simulation. The proposed model gives realistic predictions of the flow dynamics within the jet mill. Experiments are conducted on the Alpine 100AFG jet mill to study the particle size, morphology and mass of the ground product. The numerical results are found in good agreement with the experimental results.