Kebijakan Penilaian Keberhasilan Reklamasi Lahan Pasca-tambang Batubara di Indonesia

Indonesian government has enacted regulations requiring reclamation and rehabilitation activities on post coal mining areas. However, the evaluation related to the ecological restoration concepts is yet unavailable. This study aims to evaluate the regulations on rehabilitation and reclamation of post coal mining areas in Indonesia conforming on ecological restoration concepts. Employing desk study and content anaysis, this research focussed on three technical regulations concerning reclamation guidance and post-mining evaluation guidance, namely ESDM Decree No 7 Year 2014, MoF Decree No P.60/Menhut-II/2009, and MoF Decree No P.4/Menhut-II/2011. Each regulation was comprehensively evaluated whether the regulation already regulates matters relating to ecological restoration criterias, such as biodiversity recovery, soil remediation, planting of local plants, bans on invasive plant species and monitoring and evaluation. The result showed that there was no regulation complying with all ecological restoration criterias. Meanwhile, all the regulations have mandated monitoring and evaluation after rehabilitation and reclamation activities. However, there was no regulation mandating prohibition on planting invasive plant species. In conclusion, regulations related to post coal mining rehabilitation and reclamation have not fully complied with the ecological restoration concepts, therefore improvement to that regulations are necessary. Pemerintah Indonesia telah menetapkan berbagai peraturan yang mewajibkan kegiatan reklamasi dan rehabilitasi pasca-tambang, namun, belum banyak dilakukan evaluasi terhadap peraturan tersebut dalam kaitannya dengan konsep ekologi restorasi. Penelitian ini bertujuan untuk mengetahui sejauh mana peraturan-peraturan tersebut memenuhi konsep restorasi ekologi. Metode penelitian ini adalah desk study dengan bahan utama regulasi yang berkaitan dengan kegiatan reklamasi dan rehabilitasi lahan pasca-tambang batubara. Analisis data dilakukan dengan metode analisis isi. Kajian difokuskan pada tiga aturan teknis yang mengatur pedoman reklamasi maupun pedoman penilaian keberhasilan reklamasi pasca-tambang yaitu Peraturan Menteri ESDM Nomor 7 tahun 2014, Permenhut Nomor P.60/Menhut-II/2009, dan Permenhut Nomor P.4/Menhut-II/2011. Setiap peraturan Perundangan dikaji secara komprehensif apakah peraturan tersebut sudah memuat dan mengatur hal-hal yang berkaitan dengan beberapa kriteria restorasi ekologi. Hasil penelitian menunjukkan bahwa tidak ada peraturan yang memenuhi semua kriteria restorasi ekologi. Semua regulasi telah memuat kewajiban rehabilitasi atau reklamasi serta evaluasi tetapi tidak ada satupun regulasi yang memuat pelarangan penggunaan tanaman invasif. Kesimpulan penelitian ini adalah regulasi tentang rehabilitasi dan reklamasi pasca-tambang batubara di Indonesia belum sepenuhnya sejalan dengan konsep ekologi restorasi karena hanya memuat sebagian dari kriteria dan indikator restorasi ekologi sehingga masih diperlukan penyempurnaan agar perbaikan dan pemulihan lahan pasca-tambang dapat memenuhi konsep restorasi ekolog

Nonparametric Inference for Copulas and Measures of Dependence Under Length-Biased Sampling and Informative Censoring

Length-biased data are often encountered in cross-sectional surveys and prevalent-cohort studies on disease durations. Under length-biased sampling subjects with longer disease durations have greater chance to be observed. As a result, covariate values linked to the longer survivors are favored by the sampling mechanism. When the sampled durations are also subject to right censoring, the censoring is informative. Modeling dependence structure without adjusting for these issues leads to biased results. In this article, we consider copulas for modeling dependence when the collected data are length-biased and account for both informative censoring and covariate bias that are naturally linked to length-biased sampling. We address nonparametric estimation of the bivariate distribution, copula function and its density, and Kendall and Spearman measures for right-censored length-biased data. The proposed estimator for the bivariate cdf is a Hadamard-differentiable functional of two MLEs (Kaplan–Meier and empirical cdf) and inherits their efficiency. Based on this estimator, we devise two estimators for copula function and a local-polynomial estimator for copula density that accounts for boundary bias. The limiting processes of the estimators are established by deriving their iid representations. As a by-product, we establish the oscillation behavior of the bivariate cdf estimator. In addition, we introduce estimators for Kendall and Spearman measures and study their weak convergence. The proposed method is applied to analyze a set of right-censored length-biased data on survival with dementia, collected as part of a nationwide study in Canada

Time scale analysis for fluidized bed melt granulation I: granule-granule and granule-droplet collision rates

Fluidized bed spray granulators (FBMG) are widely used in the process industry for particle size growth; a desirable feature in many products, such as granulated food and medical tablets. In this paper, the first in a series of four discussing the rate of various microscopic events occurring in FBMG, theoretical analysis coupled with CFD simulations have been used to predict granule–granule and droplet–granule collision time scales. The granule–granule collision time scale was derived from principles of kinetic theory of granular flow (KTGF). For the droplet–granule collisions, two limiting models were derived; one is for the case of fast droplet velocity, where the granule velocity is considerable lower than that of the droplet (ballistic model) and another for the case where the droplet is traveling with a velocity similar to the velocity of the granules. The hydrodynamic parameters used in the solution of the above models were obtained from the CFD predictions for a typical spray fluidized bed system. The granule–granule collision rate within an identified spray zone was found to fall approximately within the range of 10-2–10-3 s, while the droplet–granule collision was found to be much faster, however, slowing rapidly (exponentially) when moving away from the spray nozzle tip. Such information, together with the time scale analysis of droplet solidification and spreading, discussed in part II and III of this study, are useful for probability analysis of the various event occurring during a granulation process, which then lead to be better qualitative and, in part IV, quantitative prediction of the aggregation rate

Time scale analysis for fluidizedbedmeltgranulation III: binder solidification rate

In series I and II of this study ([Chua et al., 2010a] and [Chua et al., 2010b]), we discussed the time scale of granule–granule collision, droplet–granule collision and droplet spreading in Fluidized Bed Melt Granulation (FBMG). In this third one, we consider the rate at which binder solidifies. Simple analytical solution, based on classical formulation for conduction across a semi-infinite slab, was used to obtain a generalized equation for binder solidification time. A multi-physics simulation package (Comsol) was used to predict the binder solidification time for various operating conditions usually considered in FBMG. The simulation results were validated with experimental temperature data obtained with a high speed infrared camera during solidification of ‘macroscopic’ (mm scale) droplets. For the range of microscopic droplet size and operating conditions considered for a FBMG process, the binder solidification time was found to fall approximately between 10-3 and 10-1 s. This is the slowest compared to the other three major FBMG microscopic events discussed in this series (granule–granule collision, granule–droplet collision and droplet spreading)

A priori prediction of aggregation efficiency and rate constant for fluidized bed melt granulation

This paper presents a predictive aggregation rate model for spray fluidized bed melt granulation. The aggregation rate constant was derived from probability analysis of particle–droplet contact combined with time scale analysis of droplet solidification and granule–granule collision rates. The latter was obtained using the principles of kinetic theory of granular flow (KTGF). The predicted aggregation rate constants were validated by comparison with reported experimental data for a range of binder spray rate, binder droplet size and operating granulator temperature. The developed model is particularly useful for predicting particle size distributions and growth using population balance equations (PBEs)

Time scale analysis for fluidizedbedmeltgranulation-II: binder spreading rate

The spreading time of liquid binder droplet on the surface a primary particle is analyzed for Fluidized Bed Melt Granulation (FBMG). As discussed in the first paper of this series (Chua et al., in press) the droplet spreading rate has been identified as one of the important parameters affecting the probability of particles aggregation in FBMG. In this paper, the binder droplet spreading time has been estimated using Computational Fluid Dynamic modeling (CFD) based on Volume of Fluid approach (VOF). A simplified analytical solution has been developed and tested to explore its validity for predicting the spreading time. For the purpose of models validation, the droplet spreading evolution was recorded using a high speed video camera. Based on the validated model, a generalized correlative equation for binder spreading time is proposed. For the operating conditions considered here, the spreading time for Polyethylene Glycol (PEG1500) binder was found to fall within the range of 10-2 to 10-5 s. The study also included a number of other common binders used in FBMG. The results obtained here will be further used in paper III, where the binder solidification rate is discussed