Expansion Problem Research Articles

Towards a complex investment evaluation framework for renewable energy systems: A 2-level heuristic approach

Renewable energy technologies still endure critical technical and financial challenges. These challenges demand for specially tailored decision support tools for planning the (renewable-based) strategical expansion of power systems. However, existing tools not always adequately integrate the tactical and operational dimensions of power systems into the evaluation process; hence, the designed investment strategies might fail to foresee how new infrastructure integrates with the existing power system and also fail to capture the volatile energy market dynamics. In this paper, this methodological gap is addressed by presenting a decision aid framework, based on mixed integer programming, for supporting long-term decision-making when planning (the expansion of existing) energy systems. The proposed framework relies on heuristically solving an optimization problem coined as the Generation, transmission and storage location and sizing of operation-aware sustainable power system design problem, which encodes two nested problems: a novel strategic renewable power system expansion problem, and a Unit Commitment problem. Using a case study from the Chilean power system, it is shown that the proposed tool ensures a more realistic and accurate economic evaluation, as it takes into account the influence of the evaluated project on the grid where it will be installed. In the considered case study, the devised framework designs a sustainable power system expansion investment strategy ensuring an investment rate of return of at least 7% and an annualized profit of more than 277 MM USD considering a 30 years evaluation horizon; furthermore, this is accomplished along with an equalization of the spot price resulting in a 13% reduction with respect to the current spot price of the system. This shows the impact of renewable sources and energy storage systems on the market operation. Furthermore, the proposed approach is used to investigate how high (public) subsidies on renewable technologies should be in order to increase the penetration of these technologies.

A robust capacity expansion integrating the perspectives of marginal productivity and capacity regret

This study addresses a capacity expansion problem (CEP). A typical CEP model usually focuses on addressing demand fluctuation for cost minimization and assumes a constant marginal productivity, which may overestimate the capacity level, thus leading to an infeasible capacity plan. However, the marginal productivity theory has some merits which can complement the CEP; for example, a production function estimates the production possibility set limiting the production behavior and characterizes the law of diminishing marginal returns (DMR). To integrate the perspective of marginal productivity factors in the CEP model, we propose a two-stage model to solve the CEP. The first stage estimates the production possibility set and finds the directional marginal productivity (DMP) towards marginal profit maximization. The second stage, which addresses demand fluctuation, develops the minimax regret model, balancing capacity shortage and capacity surplus to build a robust capacity plan. The results of a numerical illustration validate the robust decision generated by the proposed model and correct a typical CEP model without considering marginal productivity, where the major factor affecting capacity decisions is the ability to raise/leverage resource for marginal productivity rather than demand variation and cost structure.

Analisis Implementasi Kebijakan Perlindungan Lahan Gambut Untuk Tanaman Pangan Berkelanjutan

The massive expansion of oil palm plantations for the benefit of the palm oil industry and its derivatives has an impact on ecosystem and environmental damage as well as large demands for land conversion that threaten agricultural land for food crops, which also threatens food security on it. Jebus Village, Kumpeh District, Muaro Jambi Regency, Jambi Province which has peat soil type for most of its land, in this case is one of the villages facing the problem of oil palm plantation expansion and land conversion which is starting to threaten agricultural land for food crops. Therefore, the Jebus Village Regulation No.1 of 2017 concerning the Protection of Peatlands for Sustainable Food Crops and Plantations was made to protect food land in Jebus village. This study aims to analyze the implementation of peatland protection for sustainable food crops in Jebus village. This research uses descriptive qualitative methods. The collection of various data is carried out with a combination of in-depth interview and observation techniques and is supported by data from research results or reports. Data processing uses coding to obtain meaning which is presented in narrative form. This study found that the implementation of the Village Regulation was able to reduce the threat of damage to peatlands, restrain the rate of conversion of food agricultural land into plantations that were not environmentally friendly. However, the implementation of this policy has not been able to guarantee the availability of staple food (rice) for the Jebus village community. In addition, policy implementation faces challenges that cannot be resolved at the village scale.

Multi-chronological hierarchical clustering to solve capacity expansion problems with renewable sources

Renewable sources are increasing their presence in power systems to achieve the goal of decarbonizing the generation of electricity. However, the variability of these resources introduces high uncertainty in the operation of a power system and, hence, fast generating and storage units must be incorporated in the system. To obtain economically and technically efficient solutions in the capacity expansion problem, an adequate representation of the variability of the renewable resource is crucial, but this may increase the size of the problem up to computational intractability. The most suitable representation is often selected through clustering techniques. The clustering algorithms proposed in the literature suffer from a significant trade-off between their ability to capture the inter-temporal correlation of the clustered elements and the representativeness of the clusters when only very few are needed. This paper proposes an innovative clustering technique that overcomes this trade-off. A case study based on the European power system is solved. The outcomes given by the new clustering algorithm and other well-known techniques are investigated through in-sample and out-of-sample analyses applied to multiple cases that differ in to the number of clusters and the minimum renewable production.

성적 자기결정권의 헌법적 함의 - 성폭력범죄의 판단기준인 성인지 감수성을 중심으로 -

This Article goes on the Constitutional Implications of the Right of Sexual Self-Determination - Focusing on the Gender Sensitivity as Criteria of Sexual Violence -. Currently the legally abstract concept of gender sensibility is being used in sexual assault crime trials causing controversy. Therefore in this paper we examined whether gender sensitivity can function as a means or criteria for protecting or guaranteeing the sexual self-determination of victims by properly realizing the role of sexual self-determination under the constitution in sexual violence criminal trials. In order for gender sensitivity to exert the normative power to objectively and effectively protect victims right to sexual selfdetermination in sexual violence trials it is necessary to establish a basis as a universal rule of thumb for the average point of view of victims which is the criterion for judgment. It is necessary to prepare clear guidelines on the content and limitations of gender sensitivity necessary to operate as a rule of thumb in sexual violence crime trials. It is pointed out that the theoretical dialogue has not yet progressed sufficiently to use relatively unfamiliar concepts such as gender sensitivity or surprise assault as a basis for a trial. To some extent the problem of expansion of punishment based on the abstractness of sensitivity will also be solved. In the future it is necessary to align the direction of the research on the definition of the concept of gender sensitivity and the development of a criterion for judgment. If research on this continues to accumulate gender sensibility can be sufficiently established as the standard for practically realizing the right to sexual self-determination under the constitution.

Lithium-metal host anodes with top-to-bottom lithiophilic gradients for prolonged cycling of rechargeable lithium batteries

Metallic lithium (Li) is a promising anode candidate for high-energy-density Li batteries. The problems of dendrite growth and volume expansion caused by Li metal cycling can be suppressed by the introduction of a 3D conductive skeleton. However, as the cycle progresses, the Li metal deposits on the upper surface of the skeleton structure, making the host ineffective. Herein, a 3D porous host is designed comprising ZnO nanoparticles having lithiophilic gradients assemble on an interconnected 3D carbon nanotube/graphene skeleton. The 3D porous carbon nanotube/graphene structure exhibits excellent conductivity and a large specific surface area, which reduces the local current density and provides ample space for Li deposition. More importantly, the lithiophilic gradient ZnO nanoparticles anchored on the graphene sheets enable hierarchical induction of Li-ion nucleation and guide Li deposition into the host, preventing preferential deposition at the top surface of the host even during prolonged Li stripping/plating. The host delivers a high Coulombic efficiency of up to 98.2% for at least 500 cycles, and the symmetrical cell comprising the host operates smoothly for >920 h (<20 mV). The as-prepared full cell, paired with a LiFePO4 cathode, exhibits an excellent rate capability and flat surface morphology.

A cyber‐secure model to decentralized co‐expansion planning of gas and electricity networks

Flexibilities offered by gas-fired power plants have strongly increased their usage in power systems. Increasing the penetration rate of gas-fired power plants has made it necessary to coordinate gas network expansion planning with electricity network expansion planning. In this paper, a decentralized model for expansion of gas and electricity networks is introduced that coordinates investment in these networks while taking into account their privacy. Alternating direction method of multipliers is used to decompose the centralized gas and electricity expansion problem into two separate expansion problems. The proposed method aims to minimize the investment and operation cost of interconnected gas and electricity networks during the planning period. The resultant problems are mixed-integer nonlinear programs, which are then linearized and transformed into mixed-integer linear programming models to facilitate the optimality conditions. Distributed optimization provides a cyber-physical system in which gas and electricity networks are managed separately while a coordination link is provided through the cloud computing layer. However, coordinated operation through a cloud layer keeps the control-loop subject to cyber-attacks. In this paper, the standard form of the proposed decentralized model is modified to secure it against cyber-attacks. Finally, the effectiveness and applicability of the proposed method are tested and verified over a real case study that has a high penetration level of gas consuming generation units. The proposed cyber secure model not only converges faster than a standard model (ie, computationally more efficient than conventional methods) but also keeps optimality of found solution in a secure fashion. The satisfactory performance of the proposed model is also demonstrated against centralized, leader-follower, and independent expansion planning models.

Undrained Spherical Cavity Expansion in Unsaturated Soils: Semianalytical Solution Coupling Hydraulic and Mechanical Behaviors

A coupled hydromechanical solution to undrained spherical cavity expansion problem in unsaturated soil is proposed with an elastoplastic model for unsaturated soil. The mechanical response and hydraulic behavior of soil during expansion are coupled together through a soil–water characteristic curve (SWCC) that evolves with the void ratio. A system of four first-order differential governing equations is derived based on the equilibrium equation, large stain theory and coupled hydromechanical constitutive relationship of soil. The present solution can reduce to unified hardening parameter model based solution under saturated condition, which validates the proposed solution. The effects of overconsolidation ratio and initial suction on expansion responses are explored based on extensive parametric studies. Special attention is paid to investigate the distributions of the principal stresses, suction, and saturated degree of soil around the expanded cavity; the stress trajectory of a representative element at the cavity surface; and cavity pressure–displacement curves. The proposed analytical solution can serve as a theoretical framework for modelling of some fundamental geotechnical problems in unsaturated soils using critical state soil models.

Role of grid and bulk storage in the integration of variable renewable energy resources: Framework for optimal operation-driven multi-period infrastructure planning

This paper presents a unified framework for quantifying the techno-economic value of various technologies in systems with high levels of variable renewables, which is of utter importance in evaluating roadmaps towards an affordable and sustainable future for various energy industry stakeholders. The optimal planning framework is based on integrating the solution of a transmission and generation/storage expansion problem with the solution of unit commitment, with the objective to minimize the total capital and operational expenditures over a selected horizon. The formulation includes, but is not limited to, traditional thermal units, pumped-hydro storage, batteries and transmission technologies. The decision variables include new cross-zonal transmission capacity, bulk energy storage and generation capacity, which are computed over the selected horizon while accounting for the impact of wind and solar variability on hourly (or sub-hourly) basis. A reduced representative version of the European system is used to demonstrate the value of transmission and bulk energy storage for a selected set of future scenarios, including scenarios corresponding to high proliferation of distributed energy storage and e-mobility. Comparative results are presented with emphasis on the renewable energy shares, investment costs, average cost of electricity, and carbon emission targets. Sensitivity analysis is performed considering technology and fuel costs.

Structural properties and adsorption of uranyl ions on the nanocomposite hydroxyapatite/white clay

Uranium is more and more extensively applied as a source of energy and can be potentially used for nuclear weapon production. Owing to that fact, the problem of uranium expansion in the environment is the object of research and draw attention many scientists. One of the most effective methods of uranium removal from the wastewater (where uranium is present in a low concentration and occurs mainly in the form of uranyl ion, UO22+) is the adsorbent usage. It is important to discover an adsorbent which will be effective, widely available and cheap. The paper discusses properties and the ability of U (VI) adsorption on a clay and nanocomposite clay/Hap (hydroxyapatite) obtained by wet method. The adsorbents were characterized by the mentioned below tests: XRD, XRF, the porosity (nitrogen adsorption–desorption method), zeta potential, surface charge density and sorption of U (VI). It was shown that nanocrystalline composites Hap/white clay can be appropriate adsorbent for removal of uranyl ions. The adsorption depends on the temperature and pH of the solution.

Study of hygroscopic expansion of anode readout boards of gaseous detectors based on FR4

The problem of hygroscopic expansion of FR4 based large-size PCBs is discussed using the example of Micromegas detector. The readout electrodes of the detector located on the anode printed circuit board assumed to have precise dimensions. During the production and delivery process, the readout PCB is exposed to different temperature and humidity conditions. As a result, the PCB size differs from the nominal one at the moment of assembly of the detector. The problem appears to be relevant for any other large-size gaseous detectors with the readout structure based on FR4. The swelling of two test PCB samples during water absorption is studied. The size of the samples is 650× 500× 0.5 mm3. Both samples have copper strips on one side. The second side is naked on sample 1 and fully covered with a copper layer on sample 2. The elongation of the samples from dry conditions to 50% RH is measured. The influence of the copper layers on the absorption rate and the value of equilibrium elongation is discussed. It is shown that elongation of sample 1 follows the Fick's law while the absorption process in sample 2 is more complicated. The coefficient of linear hygroscopic expansion of sample 1 is measured and discussed.

Elastoplastic solution of drained expansion of a cylindrical cavity in structured soils considering structure degradation

An elastoplastic solution of drained cylindrical cavity expansion is presented based on a well-known critical state model for soils exhibiting a natural structure. The model referred to as the structured Cam-clay (SCC) model is capable of describing the properties of the soil structure and its subsequent stress-induced degradation. The asymmetric stiffness matrix of the elastoplastic constitutive equation for structured soils is derived due to the assumption of the non-associated plastic flow rule. The solution procedure is formulated by transforming the boundary value problem of cylindrical cavity expansion into the problem of solving four ordinary differential equations with three stress components and the specific volume as the basic unknown variables. The theoretical solution is numerically calculated and validated against the existing solution and finite element simulation results. Furthermore, the significance of the soil structure and its stress-induced degradation in the expansion response, and the interaction between the soil structure and overconsolidation are emphasized by extensive parametric analyses. The results demonstrate that the soil structure has a substantial influence on the cavity expansion response, and its degradation is closely related to overconsolidation. Particularly, among the solutions considered, the solution considering the soil structure provides higher effective stress values near the cavity surface due to the additional strength conveyed by the natural structure.

Three-Dimensional Ordered Porous Nanostructures for Lithium-Selenium Battery Cathodes That Confer Superior Energy-Storage Performance.

Lithium-selenium (Li-Se) batteries suffer from the problems of polyselenides dissolution and volume expansion of active materials during the charge/discharge process. Moreover, the heavy atomic mass of selenium atoms limits the capacitive property of a Li-Se battery. Porous materials as the host for selenium particles reported by previous research studies are often disordered in pore structure and nonuniform in pore size. Herein, we report that a three-dimensional (3D) nitrogen-doped carbon photonic crystal (NCPC) with an ordered, interconnected structure was synthesized via a simple method to be the host of active materials. In addition, we prepared a Se-rich Se1-xSx by introducing a small amount of sulfur into a selenium ring to reduce the molecular mass but still keep the high electronic conductivity. As cathodes for a Li-Se battery, amorphous Se-rich Se1-xSx@NCPC composites exhibited high electrochemical performance with a specific capacity of 692 mA h g-1 at 0.1 Ag1-, an excellent rate capability of 526 mA h g-1 at 3 Ag1-, and an outstanding cycling property with an ultralow decay rate of 0.0132% per cycle at 0.6 Ag1- over 1000 cycles. Moreover, the pouch cell of Se1-xSx@NCPC composites also showed a good property with an energy of 253 Wh kg-1 at 0.1 Ag1- and an outstanding rate energy of 192 Wh kg-1 at 1.5 Ag1-, manifesting great potential in practical application.

Access Control Policy Maintenance in IoT Based on Machine Learning

The rapid growth of communication networking, ubiquitous sensing, and signal processing, has promoted the development of the Internet of Things (IoT). However, the IoT is essentially dynamic and has no clearly defined network boundary, unauthorized access and data leakage may be much easier. Attribute-based access control (ABAC) can solve the problem of fine-grained access control and large-scale user dynamic expansion in complex information systems, and provides an ideal access control solution for an open network environment, which is more suitable for the dynamic access environment of IoT. However, the dynamic nature of IoT brings new challenges to access control. On the one hand, as new devices and services are continuously deployed, administrators need to manually formulate new rules, which is time-consuming and error-prone. On the other hand, as the IoT environment is continuously changing, the access policy easily becomes unsuitable for the current environment. In order to solve the above two problems, we propose a new scheme named Policy Maintenance-based machine learning (PMML), which includes two modules named Policy Generalization (PG) and Policy Evaluation (PE). After the access control model is deployed, automated PG and PE are carried out to maintain the rule set. In the PG module, we define a novel measure, resource similarity, and integrate it into policy mining so that policies could generalize among related resources. In the PE module, we introduce a quantitative method to assess rules and prune rules of low-quality. We conduct our experiments on real-world enterprise access logs from Amazon, and thoroughly analyzed the effects of different hyper-parameters on the experimental results. The experimental results have qualitatively and quantitatively shown the effectiveness of our proposed scheme.

Stromal Vascular Fraction and Amniotic Epithelial Cells: Preclinical and Clinical Relevance in Musculoskeletal Regenerative Medicine.

Musculoskeletal regenerative medicine is mainly based on the use of cell therapy to heal damaged tissues such as bone, cartilage, and tendons. Throughout the years, different cell types have been employed for the treatment of musculoskeletal diseases, in particular, mesenchymal stem cells (MSCs) derived from bone marrow (BMSCs) and adipose tissue (ADSCs). Though the results of these literature studies have been encouraging, there are some limitations, especially on long-term results. Recently, some interest has shifted towards new cell types such as the stromal vascular fraction (SVF) and amniotic endothelial cells (AECs). The aim of the present literature review is to evaluate preclinical and clinical studies that used SVF and AECs for musculoskeletal tissue regeneration. Forty-eight preclinical and clinical studies, performed in the last 10 years, were identified. Both SVF and AECs, injected or implanted with or without scaffolds, were shown to be valid alternatives, and in some ways superior, to ADSCs and BMSCs, being able to differentiate towards osteogenic, chondrogenic, and tenogenic lineages, and to promote cell and tissue regenerative potential. The use of SVF and AECs could represent a new regenerative treatment in several musculoskeletal pathologies, solving the problem of cell expansion in vitro.

Optimal Design of Pipe Networks Accounting for Future Demands and Phased Expansion using Integrated Dynamic Programming and Differential Evolution Approach

The water distribution network (WDN) design comprises determining optimal pipe sizes to achieve minimum cost pipe network to meet the required demands and performance levels. However, with time, the water demand for any region changes due to population, migration, and lifestyles, so interventions need to be made to the existing WDNs. Therefore, the capacity expansion problem consists of determining the suitable interventions at various stages such that the required demands are met at minimum cost. The present study proposed a novel methodology for planning such interventions based on Dynamic Programming (DP) formulation and presented a combined Self-Adaptive Differential Evolution and DP (SADE-DP) methodology for solving the WDN expansion problems considering life cycle costs. The methodology is applied and tested on three benchmark WDNs, namely New York Tunnel (NYT), Two loop (TL), and Blacksburg (BLA) networks, and also for a real case study of the Badlapur WDN in Maharashtra, India. The proposed model solutions are validated by comparing them with other WDN expansion methods taken from the literature. The results indicate that the proposed SADE-DP approach is computationally efficient and provides cost-effective solutions by meeting desired performance levels at various stages, and can serve as a potential alternative for solving real-world WDN expansion problems.

Why reducing socio-environmental externalities of electricity system expansions can boost the development of solar power generation: The case of Chile

In recent years, the transition towards low-carbon electricity systems has increased the development of renewable generation and, in turn, of transmission infrastructure. Importantly, developing low-carbon technologies (that are generally located far from load centers) and their associated network infrastructure, may conflict with land uses that are valuable by society (e.g. the presence of national parks, indigenous development, touristic zones, etc.). Appropriately addressing this conflict is key for policy makers and regulators to foster an effective, sustainable, and socially acceptable system expansion. In this context, this work analyzes the effects of accounting for these land-use, socio-environmental externalities on the expansion of the entire power system. For a more effective mitigation of system expansion impacts on land uses, we propose to coordinate the needed investments among the various market participants such as generation developers and network planners. To assess this proposal, we develop a two-stage stochastic program that determines the future generation and network expansions considering both (i) a balance between monetary/investment costs and their corresponding socio-environmental externality costs (derived from the land-use impacts of new electricity investments), and (ii) different levels of coordination among market participants. Hence, we can assess the benefits of various coordination strategies against the actual approach to system expansions with no coordination among developers. By running various case studies based on the Chilean electricity system by 2030, we show that recognition of socio-environmental externalities at the moment of deciding system expansions can have a significant impact on the location of future infrastructure and, remarkably, on the entire mix of new generation projects. Particularly, we found an increase in bulk, transmission-connected solar power generation capacity by circa 25% when land-use externalities are considered in the system expansion problem. This is so because bulk solar power generation projects tend to present less socio-environmental impacts (since the solar power potential is generally higher in deserts and arid regions, away from populated areas) and, up to a certain extent, have the ability to displace the need for other generation technologies, particularly hydropower, located in areas with significantly conflicting land uses. We also demonstrated the benefits of investment coordination in supporting both an increased penetration of solar power generation, and an economically effective and sustainable development of a low-carbon power system in Chile.

Analog time machine in a photonic system

Analogue physics has successfully tackled the problems of chromodynamics, event horizons, Big Bang and Universe expansion, and many others. Here, we suggest a photonic model system for a "time machine" based on the paraxial beam approximation. We demonstrate how the closed time-like curves and the well-known grandfather paradox can be studied experimentally in this system. We show how the Novikov's self-consistency principle is realized in quantum mechanics thanks to the Heisenberg's uncertainty principle.

Cavitation phenomenon in penetration of rigid projectiles into elastic-plastic targets

This paper presents an analytical study on the cavitation phenomenon during penetration of a rigid projectile into an elastic-plastic target. The developed analytical approach is based on the general solution of the quasi-static and non-stationary dynamic cylindrical/spherical cavity expansion problem with assigned kinematic boundary condition at the cavity boundary (variable, time dependent radial velocity). An analytical projectile-target separation criterion is developed for a projectile having an arbitrary shape and for a target described by a simplified material model with a locked equation of state and a linear shear failure relationship. This relatively simple model may represent the behavior of different materials reasonably well yet allow an analytical solution of the problem. The paper derives the analytical expression of the contact zone size using both the cylindrical and spherical cavity expansion approaches and presents the related normal contact stresses acting on the projectile nose surface that maintains contact with the target. Examples of the developed formulation is presented for ogive nose and Rankine ovoid projectiles hitting aluminum targets, with a constant shear failure envelope, at different velocities and comparisons with known analytical and numerical solutions are shown. The effect of projectile and medium properties on the size of the contact zone are studied.

Records management and strategic information governance – a different perspective

This article examines the differences between the two competing in foreign management sectors of scientific and practical activity &amp;ndash;records management and information governance &amp;ndash; through comparing their definitions, content, and structure. The research is based on the analysis of scientific literature and normative framework, which describe the concept and structure of record management and information governance. The authors explores the factors and stages of the formation of records management and information governance. Special attention is given to the literature review dedicated to information governance, as a developing trend, which is yet lacking the generally accepted definition. The conclusion is made on the absence of fundamental differences between the records management and information governance, which match in their key functions. There is no doubt that the problem of uncontrolled increase in the volume of information is essential for both, foreign and domestic organizations. However, this problem along with attendant problems can be solved by through the traditional scientific-practical discipline of records management; therefore, the formation of a similar discipline seems unreasonable. The conducted research is substantiated by the need to summarize foreign experience in information governance, due to the absence of such works in the domestic management theory, as well as for the development of original approaches towards solution of the problem of expansion of information in the organizations.