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This study explores the possibility of applying high-gravity rotating packed bed (HGRPB) in removing H2S and CO2 from biogas. Ca(OH)2 aqueous solution was used as the absorbent in this study. Different experimental conditions including solution pH, rotating speed (R S) of HGRPB, gas flow rate (Q G), and liquid flow rate (Q L) were investigated with respect to the removal efficiency (E) of H2S and CO2. The experimental and simulated results show that the optimal removal efficiency of H2S and CO2 using HGRPB achieved nearly the same as 99.38 and 99.56% for removal efficiency of H2S and 77.28 and 77.86% for removal efficiency of CO2, respectively. Such efficiencies corresponded with the following optimal conditions: a solution pH of 12.26, HGRPB reactor with the rotating speed of 1,200 rpm, the gas flow rate of 2.46 (L/min), and the liquid flow rate of 0.134 (L/min).

Diabetes leads to health problems for hundreds of millions of people globally every year. Available medical records of patients quantify symptoms, body features, and clinical laboratory test values, which can be used to perform biostatistics analysis aimed at finding patterns or features undetectable by current practice. In this work, we proposed a machine learning model to predict the early onset of diabetes patients. It is a novel wrapper-based feature selection utilizing Grey Wolf Optimization (GWO) and an Adaptive Particle Swam Optimization (APSO) to optimize the Multilayer Perceptron (MLP) to reduce the number of required input attributes. Moreover, we also compared the results achieved using this method and several conventional machine learning algorithms approaches such as Support Vector Machine (SVM), Decision Tree (DT), K-Nearest Neighbor (KNN), Naive Bayesian Classifier (NBC), Random Forest Classifier (RFC), Logistic Regression (LR). Computational results of our proposed method show not only that much fewer features are needed, but also higher prediction accuracy can be achieved (96% for GWO - MLP and 97% for APGWO - MLP). This work has the potential to be applicable to clinical practice and become a supporting tool for doctors/physicians.

Lemongrass essential oil has many compounds appropriate for application in foods, cosmetics, and pharmaceutical products. Of these, citral is a high-value compound of interest to industry. This work aims to evaluate the use of vacuum fractional distillation to separate lemongrass essential oil compounds, producing essential oil fractions containing high citral content. The effect of process parameters, namely vacuum pressure, type column, and energy input, on the fractionation time, content, and recovery of citral in the fractions, was investigated. The fractionation of lemongrass oils successfully provided five fractions, i.e., fraction 1 (F1), fraction 2 (F2), fraction 3 (F3), fraction 4 (F4), and fraction 5 (F5). GC-MS (Gas Chromatography-Mass Spectrometry) spectra showed that the main compound contained in F1 and F2 fractions was β-myrcene (&gt, 70%). Meanwhile, F4 and F5 were the two main fractions for citral recovery. The optimal conditions of the fractional distillation system included a column height of 400 mm, power input of 165 W, and pressure of 15 mmHg. These conditions correspond to the highest total citral content of 95%, with a recovery of 80% at the F4 and F5 fractions. Therefore, fractional vacuum distillation may be an effective method to upgrade lemongrass essential oil.

Cardiovascular diseases kill approximately millions of people globally every year. Heart failure (HF) occurs when the heart cannot pump enough blood to meet the needs of the body. This means that the heart is overworked and unable to respond to the speed and demands of other activities. This will lead to fatigue and shortness of breath while performing daily activities. In this research, the authors apply a machine learning model to predict heart failure patients’ survival based on the original set of available medical features. Therefore, a novel wrapper-based feature selection utilizing an Adaptive Particle Swarm Grey Wolf Optimization (APSGWO) is proposed to enhance the architecture of Multilayer Perceptron (MLP) and reduce the number of required input attributes. Moreover, we also compared the results of our proposed method and several conventional machine learning models such as Support Vector Machine (SVM), Decision Tree (DT), K–Nearest Neighbor, Naive Bayesian Classifier (NBC), Random Forest (RF), and Logistic Regression (LR). The results of our method show not only that much fewer features are needed, but also higher accuracy can be accomplished, 81% for Adaptive Particle Swarm Grey Wolf Optimization—Multilayer Perceptron (APSGWO—MLP). This work can be applied in practice to become an effective tool to support the diagnosis for doctors.

Recently, there has been a growing interest in artificial neural networks, a rough simulation of the human brain's information processing ability, as modern and vastly sophisticated computational techniques. This interest has also been reflected in the water and wastewater field. This chapter presents a review of articles on the application of neural networks as useful tools to solve various problems in wastewater fields, especially those characterized by pollutants prediction. After a short description of theoretical background and practical basics concerning the computations performed employing neural networks, the essential water and wastewater applications of neural networks are demonstrated with suitable references. The considerable role of neural networks in prediction, simulation, optimization, and searching for the relationships between each parameter and treatment efficiency is discussed.

Many developing countries have struggled with realizing sufficient revenues from property tax. However, as developing countries experience economic growth, they are also seeing property values rising, providing a bigger tax base from which to realize revenues. Technology has made tax administration easier and more effective and developing country governments have been improving their quality of governance and considering introducing or enhancing property tax revenue collection to diversify their tax and fiscal revenues. This paper explores the determinants of property tax revenue using data from the United States, Canada, Australia, Chile, and the Organisation for Economic Co-operation and Development for 2006 to 2016, using a fixed effects model. The results show that increases in gross domestic product and population lead to increases in property tax revenue and an increase in federal transfers decreases it. The outcomes of the empirical analysis highlight the statistically significant impacts on property tax collection of a country's state of development and its demographic, fiscal, and property tax?specific characteristics. A critical question for further research is whether and how the empirical methodologies and specifications as applied to the set of developed economies would be replicated in the context of developing countries.

The effects of ultrasonic and ozonation pretreatments on organic solubilization, anaerobic biodegradability, and biogas production were elucidated in this study. Two pretreatment methods for batch anaerobic digestion for biogas recovery with the same material and experimental conditions were the focus for comparison. Anaerobic digestion experiments were conducted at ambient temperature with the solid retention time set to 25 days. The obtained results indicated that the soluble chemical oxygen demand increased from 0.344 without pretreatment to 1.023 and 1.228 g/L with ultrasound and ozone pretreatments, respectively, whereas the yields of biogas production in the 25 days increased by 32.3 and 52.9% via ultrasonic irradiation and ozonation relative to the control case, respectively. The biodegradability of the organic compounds of the samples for the cases of ultrasound, ozone pretreatments, and control achieved 55.9, 64.31, and 39.18%, respectively, in terms of chemical oxygen demand (COD) removal efficiencies. The physicochemical characteristics of sludge flocs were investigated via scanning with particle sizes, which were obviously affected by pretreatments of sonication and ozonation, resulting in finer particles than in the control case.

We study a classical lattice dipole gas with low activity in dimension \({d \geq 3}\). We investigate long distance properties by a renormalization group analysis. We prove that various correlation functions have an infinite volume limit. We also get estimates on the decay of correlation functions.

The main objective of this paper is to provide support for the World Bank’s task team leaders of PERs that would include a chapter on taxation. It seeks to provide broad guidance for the TTLs to: (a) Lead dialogues with client countries on the scope of the tax chapter in view of Government’s on-going and planned reforms of tax policy and/or tax administration; (b) Evaluate the magnitude of data requirements and limitations in the country-specific context; and (c) Establish an appropriate team, particularly consider selection of technical staff or consultant and discuss with the team on scope of the chapter on taxation and suitable analytical tools and techniques to be applied. The paper may also serve as a helpful input on tax components in the preparation of lending operations, in this way supplementing other diagnostic tools. To serve these objectives, the paper aims to presents an overview of major taxes and respective list of data requirements as well as possible sources; tool and techniques in assessing the efficiency, effectiveness and equity in tax policy design (at both national and sub-national levels) and tax administration. In doing so, the authors acknowledge that this is not a straightforward task. No one-size-fits-all approach would exist to covering the revenue chapter, and this is driven by the complexities on the ground in terms of (1) the existing literature, and the mismatch between rigorous application of appropriate tools and techniques on the one hand and data available on the other; (2) existence of or immediate plan for parallel studies on tax revenues (including the IMF TA on tax policy and administration being provided); (3) the country’s economic structure, including the factors such as country’s abundance of extractive resources or aid dependence; and (4) the government’s requests for further support in revenue mobilization (tax policy or administration or both). This paper consists of four parts. The first part discusses major taxes at the national or central level of government with a reference to generally accepted notion or principles of a ‘good’ tax system. Part two is focused on the major tools and techniques for analysis of the performance of a tax system and of tax expenditures. The discussion of revenue modeling covers different methods, such as GDP based, micro-simulation, national accounts/inputs-outputs tables based and regression analyses. Part three sheds light on subnational government taxation. It covers the revenue issues at both at the regional and local levels. In addition, it introduces a framework on measuring taxing powers at subnational level, with a view to ensure appropriate ground for the fiscal dialog across levels of government. Finally, part four points to potential questions to assist in assessing the strengths and weaknesses in tax administration, drawing on Jit Gill (2000) and the newly developed tax administration diagnostic tool TADAT (2016).

This chapter focuses on the concept and empirical estimation of tax effort around the world. It employs a cross-country study from a sample of 121, developing and developed countries during 1994-2012. Predicted tax revenue of a country is estimated empirically taking into account its specific economic, demographic, and institutional features and is considered as an approximation of its taxable capacity. Tax effort is then defined as the ratio between the share of the actual tax collection and the predicted tax revenue. The use of tax effort and actual tax revenue collection allows us to rank countries into four different groups. The results vary per country and region but, overall, tax revenue collection appears to be in line with its predicted value. This could reflect many efforts undertaken in the last decades to improve tax policy and tax administration. It also suggests that further improvements in domestic revenue mobilization may require other non-tax reforms aimed at removing economic, demographic and institutional constraints hindering tax revenue performance.

While debt-financed productive public investment raises a country’s debt ratios in the short run, it can also generate higher growth, revenues, and exports, leading over time to lower debt ratios. This paper develops a framework to assess whether countries meet the conditions for realizing the net benefits over the costs of public investment debt financing. While it is possible to achieve debt sustainability with an appropriate mix of concessional and non-concessional financing, this is a necessary but not sufficient condition. It is also important to ensure the operational viability of public investment projects by having in place adequate project management: (i) project screening and appraisal, (ii) a clear connection between capital and recurrent expenditures once the projects are launched, and (iii) safeguards for appropriate project implementation and facilities operations. To illustrate the strength of these results, the paper carries out three measurement exercises: (a) a simulation of the degree to which the ratio of optimal public investment responds to changes in key parameters related to project management in a general equilibrium model; (b) application of the public investment management (PIMa) index to benchmark a country's public investment management capacity; and (c) presentation of the results of the Investment, Savings, and Macroeconomic Vulnerabilities tool aimed at tracking country choices in public finance and the impact of public projects on private investments.

Noting that Africa’s resource-rich countries have not translated their wealth into sustained economic growth and poverty reduction, this paper shows that by transferring a portion of resource-related government revenues uniformly and universally as direct payments to the population, some countries could increase both private consumption and the provision of public goods, and thereby reduce poverty and enhance social welfare. We make the case based on theoretical considerations and explore how these direct dividend payments would look in practice in a group of selected African countries.

Popular expectations for more public infrastructure services (i.e., hospitals, schools, roads) run high in Ghana because of recently discovered major oil and gas reserves in its’ offshore deposits. However, Ghana doesn’t have a good track record of using natural resource revenues, be it gold or cocoa, efficiently and effectively for development. The hard fact is that despite significant gold and cocoa revenues, the country has always experienced chronic infrastructure “deficit.” It is unclear if the surge in oil revenues did translate into better development outcomes, whereas the sharp drop in oil prices would translate into more prudent allocation and use of capital budget. Weak and politicized public investment (PIM) system in Ghana exacerbates the potential cyclicality problems of natural resource revenues. To avoid these double traps of weak institutions and cyclicality, Ghana should find an appropriate strategy to “invest in the capacity to invest.” This paper employs an indicator based framework developed by Rajaram et al. (2010) to explore efficiency and efficacy of Ghana’s PIM system. Our diagnostic assessment indicates that a number of critical functions in the Ghanaian PIM system, such as project proposal screening, appraisal, monitoring and evaluation, either exist only on paper or are completely missing.Keywords: Public Financial Management, Ghana Public Investment Management, Infrastructure Investment, Economic Development, Infrastructure Financing

The review of Mozambique’s tax system highlights some key features. The country has established a solid legal framework for taxation. The overall tax intake is buoyant. The regime remains, however, in the process of transition. Tax burden on the corporate sector is relatively high compared with other SDAC countries. The complexity of tax regime, the mere existence of multiple schemes for small and medium taxpayers across tax codes, and the post 2009 overly generous system of fiscal incentives set in favor of certain types of investment, particularly capital-intensive, new mega projects—are among the few that collectively reflect the incoherence in the policy making spanning over the past decade. To set stage for policy recommendations for furthering the reforms of major taxes, this paper provides some estimates of productivity of CIT and VAT from regional perspectives. The analysis reconfirms the complexity and erosion of the base as a major channel for revenue leakage that more than compensating for the relatively high statutory rates in these taxes.Keywords: Mozambique Tax System, Tax Productivity Measurement

One of the important factors for economic development is the existence of an effective tax system. This paper deals with the concept and empirical estimation of countries' taxable capacity and tax effort. It employs a cross-country study from a sample of 110 developing and developed countries during 1994-2009. Taxable capacity refers to the predicted tax-to-gross domestic product ratio that can be estimated empirically, taking into account a country's specific macroeconomic, demographic, and institutional features, which all change through time. Tax effort is defined as an index of the ratio between the share of the actual tax collection in gross domestic product and taxable capacity. The use of tax effort and actual tax collection benchmarks allows the ranking of countries into four different groups: low tax collection, low tax effort; high tax collection, high tax effort; low tax collection, high tax effort; and high tax collection, low tax effort. The analysis provides broad guidance for tax reforms in countries with various levels of taxable capacity and revenue intake.

In 2010, after two decades of rapid economic growth, Vietnam passed the threshold to become a lower-middle-income economy. Sustained market-oriented reforms combined with intensive efforts to integrate into the world economy are among the key drivers of this achievement. The reform of tax policy and administration has been a vital part of this transition. This is leading to a fundamental change in the composition of taxpayers, from large state-owned enterprises (SOEs) and foreign-invested companies to a myriad of small and medium private enterprises. Economic transition is also leading to an equally important change in the sources of government revenue, away from cross-border trade-related taxes and revenue collection from crude oil toward a greater share of domestic tax revenue, in particular taxation of business profits, labor income, and capital gains on land. However, completing the transition to a market economy will require changes going beyond tax collection and administration procedures, and will involve changes to the tax instruments themselves. At the end of this process, Vietnam should have a set of taxes that is simple and transparent, secures a stable flow of revenues for the government, encourages an efficient allocation of resources, and does not risk constituting a source of inequality or unfairness. The purpose of the series of studies in this volume is to shed light on the issues Vietnam will be facing in the process of reforming its tax policy and administration. The studies are also expected to lead to concrete policy recommendations contributing to the preparation of key policies and legislative documents to ensure the achievement of the state budget revenue target and other tax administration reform targets in the SEDP 2011-2015. It is expected that the individual studies in this series will become useful inputs into the debate surrounding the issuance of new laws and regulations. It is also hoped that the volume will support the reform momentum in the tax policy area, leading to increased efficiency, transparency, and equity.

The relatively slow pace of Nigeria's development has often been attributed to the phenomenon of the resource curse whereby the nature of the state as a "rentier" dilutes accountability for development and political actors are able to manipulate institutions to sustain poor governance. The impact of the political elite's resource-control and allocation of revenues on core democratic mechanisms is central to understand the obstacles to development and governance failure. Given that problems of petroleum sector governance are extremely entrenched in Nigeria, the key question is whether and how it is possible to get out of a poor equilibrium after fifty years of oil production. This paper uses a political economy perspective to analyze the governance weaknesses along the petroleum sector value chain and attempts to establish the links between challenges in sector regulation and the following major political and economic attributes: (i) strong executive control on petroleum governance in a political environment of weak checks and balances; (ii) regulatory and operating roles bundled into one institution, thereby creating conflict of interest; and (iii) manipulation of elections and political appointments. The restoration of democratic government has helped improve transparency and management of oil revenue and reforms at the federal level and proposed reforms of the petroleum sector hold much promise. At the same time, the judiciary has started to restore confidence that it will serve as a check and balance on the executive and the electoral process. Yet, these reforms are fragile and need to be deepened and institutionalized. They must be addressed not as purely technocratic matters but as issues of political economy and vested interests that must, through regulation and reform, be aligned with the public interest and a vision of Nigerian development.

With a focus on the institutional set-up and the political environment as central to understanding and rectifying the poor impact of mining on Ghana's economic development, this paper highlights the vulnerabilities in mining sector governance along the industry value chain. The authors explain why it has been difficult to implement policies that would have improved social welfare. They find that incentive problems in institutions directly or peripherally involved in mining governance are a major factor, as are an excessively centralized policy-making process, a powerful executive president, strong party loyalty, a system of political patronage, lack of transparency, and weak institutional capacity at the political and regulatory levels. The paper argues that the net impact of mining on economic development is likely to be enhanced with appropriate reforms in governance. Most importantly, there should be a greater awareness of incentive problems at the political level and their possible implications for sector performance and the economy at large. The set of checks and balances, as stipulated by the Constitution, have to be reinforced. Furthermore, capacity building at different levels and institutions is needed and should be combined with efforts to enhance incentives for institutional performance.

To enhance efficiency of public spending in oil-rich economies, this paper proposes that some of the oil revenues be transferred directly to citizens, and then taxed to finance public expenditures. The argument is that spending that is financed by taxation — rather than by resource revenues accruing directly to the government — is more likely to be scrutinized by citizens and hence subject to greater efficiency. We develop the case as follows: First, we confirm that public expenditure efficiency is lower in oil-rich countries compared with other developing countries. Second, we develop a theoretical model to explain why citizens’ scrutiny over public expenditure can be increased by transferring oil revenues to citizens and then taxing them. By receiving transfers and then paying taxes, citizens are better informed about the level of government revenue, and they have an incentive to ensure that their taxes are spent on public goods. Third, we show empirically that enhanced citizens’ scrutiny is associated with more efficient government spending decisions and that accountability is stronger in countries that rely more on taxation to finance public spending. We conclude that, while it may be difficult to implement such a proposal in existing oil producers, there is scope for introducing it in some of Africa’s new oil producers.

This paper provides a pragmatic and objective diagnostic approach to the assessment of public investment management systems for governments. Since weaknesses in public investment management can negate the core argument that additional fiscal space allocated to public investments could enhance future economic prospects, attention to the processes that govern public investment selection and management is critical. The paper begins with a description of eight key"must-have"features of a well-functioning public investment system: (1) investment guidance, project development, and preliminary screening; (2) formal project appraisal; (3) independent review of appraisal; (4) project selection and budgeting; (5) project implementation; (6) project adjustment; (7) facility operation; and (8) project evaluation. The emphasis is placed on the basic processes and controls (linked at appropriate stages to broader budget processes) that are likely to yield the greatest assurance of efficiency in public investment decisions. The approach does not seek to identify best practice, but rather to identify the"must have"institutional features that would address major risks and provide an effective systemic process for managing public investments. The authors also develop a diagnostic framework to assess the main stages of the public investment management cycle. In principle, the identification of core weaknesses will allow reforms to focus scarce managerial and technical resources where they will yield the greatest impact. In addition, the framework is intended to motivate governments to undertake periodic self-assessments of their public investment systems and design reforms to enhance the productivity of public investment.

This paper proposes that, to increase the efficiency of public spending in oil-rich economies, some or all of the oil revenues be transferred to citizens, and fiscal instruments such as taxation be used to finance public expenditures. The authors develop the case as follows. First, they confirm the well-known result that public-expenditure efficiency is lower in oil-rich countries compared with other developing countries. Second, they show that this efficiency gap is associated with differences in accountability to citizens of government's spending decisions. They find that various measures of accountability are systematically weaker in oil-rich countries. They attribute this difference to the fact that oil revenues typically accrue directly to the government, unlike tax revenues, which pass through the hands of citizens. Third, they show that, controlling for a number of factors, accountability is stronger in countries that rely more on direct taxation to finance public spending. They conclude that accountability, and hence public expenditure efficiency, can be increased by transferring oil revenues to citizens and then taxing them to finance public spending. The paper reviews existing schemes that redistribute oil revenues to the population, such as the Alaska Citizen Fund, to assess the feasibility of a modest proposal in African countries. The authors conclude that, while it may be difficult to implement such a proposal in existing oil producers, there is scope for introducing it in some of Africa's new oil producers.

An effective tax system is fundamental for successful country development. The first step to understand public revenue systems is to establish some commonly agreed performance measurements and benchmarks. This paper employs a cross-country study to estimate tax capacity from a sample of 104 countries during 1994-2003. The estimation results are then used as benchmarks to compare taxable capacity and tax effort in different countries. Taxable capacity refers to the predicted tax-gross domestic product ratio that can be estimated with the regression, taking into account a country's specific economic, demographic, and institutional features. Tax effort is defined as an index of the ratio between the share of the actual tax collection in gross domestic product and the predicted taxable capacity. The authors classify countries into four distinct groups by their level of actual tax collection and attained tax effort. This classification is based on the benchmark of the global average of tax collection and a tax effort index of 1 (when tax collection is exactly the same as the estimated taxable capacity). The analysis provides guidance for countries with various levels of tax collection and tax effort.

This publication consists of seven chapters: building a system for public investment management; a unified framework for public investment management; country experiences of public investment management; approaches to better project appraisal; public investment management under uncertainty; procurement and public investment management; and public investment management for public-private partnerships.