Cenological measurement of productive efficiency

The article shows the big concern that is caused by the problem of spatial economical and industrial bias. The decision of the given problem by classical methods did not bring the required result testifying that such politics is based on wrong or inadequate diagnosis of the bias reason, as well as the lack of qualitative search of benchmarking target state. The authors offer to consider a spatial and industrial bias not only as economically inefficient, but also non-equilibrium result of regulation politics. Thus, the balance can be considered as some economically-effective recombination of subjects of regional economy or branch enterprises. It is shown that the proposed approach does not reflect the system features of real objects (region, branch etc.) to full extent as it uses a mechanical statistical combination theory, without considering the features of considered systems, being oriented to the model which is not achievable in practice. The given downside is offered to eliminate by applying coenosis theory which uses laws of existence and development of complex systems (type “branch”, “region” etc.), relying on numerous researches in various fields of knowledge. The opportunity to calculate and to generate a specified distribution option allows to use it as the starting point of recombination for more accurate definition of potential-efficiency of the structure of a branch.peer-reviewe

Average revenue efficiency and optimal scale sizes in stochastic data envelopment analysis: A case study of post offices

Estimating the revenue efficiency of entities being evaluated is crucial as it provides valuable information about organizations, assuming that the output prices are known. This research introduces a new definition of optimal scale size (OSS) based on maximizing the average revenue efficiency (ARE). Additionally, the ARE is defined for both convex and non-convex sets, independent of returns to scale and the assumption that the vector of input-output prices of units is uniform. Moreover, to address the presence of uncertain data in real-world applications, the introduced ARE model is extended to evaluate systems with random inputs and outputs, along with approaches for its calculation. Finally, the proposed method is applied in an experimental example, calculating the ARE for a dataset of postal areas in Iran.IntroductionThe concept of optimal scale size has been extensively studied in the field of data envelopment analysis. Cesaroni and Giovannola's research on non-convex FDH technology reveals that the optimal scale size is a point in the production possibility set that minimizes average cost efficiency. Average cost efficiency, a new measure combining scale and allocation efficiencies, provides a more accurate performance assessment compared to cost and scale efficiencies. When evaluating units with known output prices instead of input prices, assessing revenue efficiency can offer more valuable insights. This paper extends the research on cost evaluation to revenue evaluation. It introduces the concepts of average revenue efficiency and optimal scale size based on revenue maximization. The optimal scale size based on revenue maximization is defined as the point in the production possibility set that maximizes the average radial income for the unit under investigation. Average revenue efficiency serves as an evaluation measure of unit revenue, surpassing revenue and scale efficiencies in accuracy. The paper examines methods for calculating average revenue efficiency in both convex and non-convex technologies. It demonstrates that the average revenue efficiency model in convex technology with variable returns to scale is equivalent to the revenue model with constant returns to scale. Furthermore, the relationship between optimal scale size points based on revenue maximization and the most productive scale size is determined. Next, the paper presents the average revenue efficiency model for stochastic sets with the presence of stochastic data. An experimental example is used to calculate the average revenue efficiency and obtain the optimal scale size for a set of postal areas in Iran.Materials and MethodsThe study builds upon Cesaroni and Giovannola's method for calculating average cost efficiency and optimal scale size to develop models for average revenue efficiency and optimal scale size based on revenue. It also utilizes chance-constrained probabilistic models with a deterministic objective function in DEA literature to present average revenue efficiency for stochastic sets. The model is transformed from stochastic to deterministic and then converted into a linear model using the error structure method.Discussion and ResultsThis paper introduces average revenue efficiency and optimal revenue scale size, demonstrating the equivalence between the average revenue efficiency models in convex technology with variable returns to scale and those with constant returns to scale. It also presents the average revenue efficiency model for stochastic sets, enabling the calculation of average revenue efficiency and optimal revenue scale size for units with random inputs and outputs.ConclusionIn many real-world scenarios, particularly when output prices are known, evaluating revenue efficiency holds greater significance than cost efficiency. This study develops the concepts of average cost efficiency and optimal scale size for revenue evaluation, expanding upon the existing literature on data envelopment analysis. The paper demonstrates how average revenue efficiency can be calculated as a valuable and accurate measure of efficiency in convex and non-convex technologies, without making assumptions about returns to scale. By assuming the randomness of input and output variables and employing chance-constrained models, a quadratic deterministic model is presented to calculate average revenue efficiency. It is then transformed into a linear model assuming uncorrelated variables, enabling the determination of average revenue efficiency and optimal scale size based on revenue maximization for random units. The proposed models are applied to a real-world sample, evaluating the average revenue efficiency of twelve postal units. The results highlight the models' ability to provide a more accurate evaluation of revenue efficiency and identify the best revenue scale size as the reference for inefficient units

Gestión de activos en estaciones depuradoras de aguas residuales: una aproximación económica

El ciclo del agua, desde la captación hasta el vertido, es un sector que implica una importante inversión en infraestructuras urbanas. En particular, las estaciones depuradoras de aguas residuales (EDARs) juegan un importante papel en la sociedad, evitan que diversos contaminantes lleguen al medio, favorecen la recarga de acuíferos y garantizan caudales mínimos. Con el fin de llevar a cabo la depuración de las aguas residuales son necesarios un conjunto de tratamientos fisicoquímicos, el grado de tratamiento requerido para el agua residual depende fundamentalmente de los límites de vertido para el efluente. La mayor parte de las instalaciones disponen de un tratamiento de tipo convencional, el cual consta de un pretratamiento, un tratamiento primario y un secundario. A su vez, los distintos procesos mencionados implican el uso de una gran variedad de activos y se pueden agrupar en construcción civil, tuberías y equipamiento electromecánico. En estas últimas décadas el número de EDARs ha aumentado de forma considerable, debido principalmente a las distintas normativas que han ido, paulatinamente, incrementando las exigencias en cuanto a seguridad ambiental. En concreto la Directiva 91/271/CEE supuso la construcción de un gran número de estaciones depuradoras debido a la obligación de que todas las aglomeraciones urbanas con más de 2.000 habitantes equivalentes dispusieran de colectores y plantas de tratamiento. Actualmente la gran mayoría de EDARs supera o está próxima a superar su vida útil y su condición estructural decrece a lo largo del tiempo. El deterioro de la infraestructura implica obtener menores rendimientos y asumir mayor número de fallos, debido principalmente a la fatiga de los materiales. Además, el deterioro que sufren no solo pone en jaque la sostenibilidad presente y futura de las plantas de tratamiento de aguas residuales, también incrementa el riesgo de accidente y la probabilidad de sufrir un impacto ambiental derivado. Los operadores públicos y privados, con tal de hacer frente al deterioro y sus consecuencias económicas y ambientales, han mostrado un gran interés en desarrollar programas orientados a los mantenimientos y reparaciones en estas instalaciones. Conocer el impacto económico asociado al envejecimiento permite planificar los reemplazos, así como optimizar los costes de mantenimiento asociados. Por este motivo, en el artículo; “Cost analysis of the facilities deterioration in Wastewater Treatment Plants: A dynamic approach” se desarrolla una función económica que explica los costes de mantenimiento y reparaciones en las EDARs teniendo en cuenta, además de la edad de la planta, sus características técnicas. Entender las consecuencias económicas del deterioro permite abordar la gestión de activos desde una óptica económica, ayudando a los tomadores de decisiones a disminuir la incertidumbre con respecto a la renovación de estas infraestructuras. Una vez modelizado el impacto del deterioro sobre los costes de mantenimiento en las infraestructuras de depuración de aguas residuales, se evalúa la influencia de estos costes en la eficiencia de las EDARs desde un punto de vista económico y ambiental. En el siguiente artículo; “Efficiency of wastewater treatment facilities: The influence of scale economies” se estudia, en primer lugar, los efectos de las economías de escala en el sector y, en segundo, el comportamiento de los costes desagregados que constituyen el proceso de depuración ante su posible influencia. Los resultados constatan que un mayor tamaño de las EDARs (según habitantes equivalentes tratados) supone una reducción global de los costes. Para ello, se identifican las distintas dimensiones que generan estos cambios de eficiencia en las plantas. Además, se señalan aquellos costes con mayor capacidad de mejora, siendo los relativos a la energía usada en el proceso y los mantenimientos realizados. Estos últimos muestran cierta heterogeneidad ya que se observa que las EDARs que tratan menos de 8.000 habitantes equivalentes anuales presentan niveles de eficiencia dispares. Este hecho pone de manifiesto que las políticas orientadas a los mantenimientos preventivos pueden incidir en un menor número de reparaciones y, en consecuencia, ayudaría a reducir los costes generales dedicados a las averías en planta. Finalmente, en el último artículo; “Preventive maintenance versus cost of repairs in asset management: An efficiency analysis in wastewater treatment plants” se analiza la relación entre los mantenimientos preventivos y las reparaciones en las instalaciones de tratamiento de aguas residuales. Este planteamiento resulta novedoso y de gran relevancia por dos motivos, en primer lugar, el cálculo de eficiencia en las instalaciones tendrá en cuenta la minimización de factores que puedan perjudicar al proceso, es decir las roturas y reparaciones que tienen lugar en estas infraestructuras. En este sentido, un mayor coste económico debido a las reparaciones penalizará la eficiencia global de la EDAR analizada. En segundo lugar, obtener un índice de eficiencia asociado a cada entrada y la salida no deseada permite analizar, a posteriori, las implicaciones de las distintas políticas de mantenimiento preventivo llevadas a cabo en las EDARs analizadas. Las conclusiones permiten establecer los niveles de costes dedicados a los mantenimientos preventivos que minimizan las averías y, además, sugieren unos costes óptimos a partir de las EDARs que mayores eficiencias ofrecen al respecto.The urban water cycle, from water collection to discharge, is a process that requires significant investment in urban infrastructure. In particular, wastewater treatment plants (WWTPs) play an important role in society, minimizing the environmental impact of wastewater, favouring the recharge of aquifers, and guaranteeing minimum flow rates. To carry out the purification of the wastewater, a set of physicochemical treatments are necessary, whose pollutants removal will depend fundamentally on the discharge limits of the receiving environment. Most of the facilities have a conventional treatment, which consists of a pretreatment, a primary and a secondary treatment. In turn, the different processes mentioned involve the use of a great variety of assets and can be grouped into civil construction, pipes and electromechanical equipment. In recent decades, the number of WWTPs has increased considerably, mainly due to different regulations that have gradually increased the demands in terms of environmental safety. Specifically, Directive 91/271 / EEC involved the construction of a large number of WWTPs due to the obligation for all urban agglomerations with more than 2,000 equivalent inhabitants to have collectors and treatment plants. Currently, the vast majority of WWTPs exceed or are close to exceeding their useful life and their structural condition decreases over time. The deterioration of the infrastructure implies obtaining lower yields and assuming a greater number of failures, mainly due to the fatigue of the materials. Furthermore, the deterioration they suffer not only jeopardizes the present and future sustainability of the wastewater treatment plants, but also increases the risk of accident and the probability of suffering a derived environmental impact. In order to face deterioration and its economic and environmental consequences, public and private operators have shown great interest in developing programs aimed at the maintenance and repairs of these facilities. Being aware of the economic impact associated with aging makes it possible to plan replacements, as well as to optimize the associated maintenance costs. For this reason, in the article “Cost analysis of the facilities deterioration in Wastewater Treatment Plants: A dynamic approach” an economic function that explains the maintenance and repair costs in WWTPs is developed taking into account the age of the facility and its technical characteristics. Understanding the economic consequences of deterioration makes it possible to approach asset management from an economic perspective, helping decision makers to reduce uncertainty regarding the renovation of these infrastructures. Once the impact of the deterioration on the maintenance costs of the wastewater treatment infrastructures has been modeled, the influence of these costs on the efficiency of the WWTPs is evaluated from an economic and environmental point of view. In the article “Efficiency of wastewater treatment facilities: The influence of scale economies” firstly, the effects of economies of scale in the sector and, secondly, the behavior of the disaggregated costs that constitute the purification process before its possible influence are studied. The results confirm that a larger WWTPs (according to equivalent inhabitants treated) implies a reduction of their costs. For this, the different dimensions that generate these efficiency variations among the facilities are identified. In addition, those costs that could be reduced have been identified, being those related to the energy used in the process and the maintenance. The latter show certain heterogeneity since it is observed that the WWTPs that treat less than 8,000 equivalent inhabitants per year present different levels of efficiency. This fact shows that policies aimed at preventive maintenance can have a lower number of repairs and, consequently, would help to reduce the costs for plant breakdowns. Finally, the last article, "Preventive maintenance versus cost of repairs in asset management: An efficiency analysis in wastewater treatment plants", analyzes the relationship between preventive maintenance and repairs in wastewater treatment facilities. This approach is novel and highly relevant for two reasons. Firstly, the efficiency calculation in the facilities will consider the minimization of factors that may harm the process, that is, the breakages and repairs that take place in these infrastructures. In this sense, a higher economic cost due to repairs will penalize the overall efficiency of the WWTP analyzed. Secondly, obtaining an efficiency index associated with each unwanted input and output makes it possible to analyze, afterwards, the implications of different preventive maintenance policies carried out in the WWTPs analyzed. The conclusions make it possible to establish the levels of costs dedicated to preventive maintenance that minimize breakdowns and, furthermore, suggest the optimal costs that WWTPs should incur taking into account the information of those WWTPs that offer greater efficiencies in this regard