Identification Of Bottlenecks Research Articles

What Do We Know When? Modeling Predictability of Transit Operations

Predictions of transit delays are crucial to passengers and operators. Passengers utilize the predictions to decide on departure time, route choice, and mode choice, whereas operators decide on schedules, timetables, rolling stock allocation, and control actions. We introduce the concept of predictability of transit travel times as the study of the reduction of the predicted variability with the temporal approaching of a predicted event. We evaluate predictability on a real-life test case in Zurich, Switzerland, spanning multiple transit lines over one year of operations. The concept is shown based on predictions obtained by a state-of-the-art Bayesian network approach, where we show how predictability (in general) can be modeled as an exponential decay phenomenon. The study of predictability of transit operations leads to additional insights for control actions and system analysis compared to other complementary concepts such as punctuality or regularity, for instance, concerning bunching, identification of bottlenecks, and passenger routing.

Innovative Approach to Assessing Safety Culture in Enterprise Personnel Management System

The article examines the safety culture of modern enterprises from the standpoint of safety-oriented approach within five components: teamwork, organizational component, functional component, identification of bottlenecks, and "work on mistakes" risk minimization. This position for highlighting the structural elements of security culture is explained by the possibility of covering all components of economic security of enterprise and management system, with emphasis on actions and reactions of direct performers and managers at different levels. The article describes the procedures for assessing safety culture, which includes nine stages. One of the main elements of such an assessment is the use of an appropriate questionnaire, which, with anonymity and prompt processing allows us to establish the real situation with the level of safety culture at an enterprise. The assessment of the level of safety culture was carried out on the example of five enterprises, and it was determined the stage for each of them (pathological, reactive, calculative, proactive, generative). Management decisions and certain measures to improve its level are taken based on the results of a comprehensive assessment, which in turn directly affects the economic security of an enterprise.

Assessing the entrepreneurial ecosystem of Sweden: a comparative study with Finland and Norway using Global Entrepreneurship Index

PurposeThis paper aims to investigate and examines Sweden's overall entrepreneurship performance (ecosystem) by applying the Global Entrepreneurship Index (GEI) while benchmarking the entrepreneurial ecosystem of Sweden with that of Finland and Norway.Design/methodology/approachIn terms of subindices, pillars and component factors, this research analyzes the entrepreneurial ecosystem of Sweden using the GEI supplemented by the Penalty for Bottleneck (PFB) approach utile for identification of bottlenecks. In addition, the Swedish ecosystem is benchmarked against its Finnish and Norwegian counterparts drawing on data collected between 2015 and 2018.FindingsUsing data drawn from the GEI, Sweden manifests a strong entrepreneurial ecosystem with a GEI score of 72.7 out of 100. However, fledgling start-up skills, insufficient human capital, and slow and erratic growth undercut otherwise solid entrepreneurial aspirations drawing on well-developed institutional variables. On a macrolevel, Sweden evinces greater capacity for entrepreneurship and innovation than either Norway or Finland but, on a microlevel, several discontinuities manifest in terms of subindices, pillars and component factors to the advantage of Norway and/or Finland and, conversely, to the detriment of Sweden.Practical implicationsPolicymakers should fund a mix of programs and institute regulatory reforms designed to promote entrepreneurial systemic development in Sweden by remediating entrepreneurial gaps depressing GEI scores. Crucial policy interventions are required to accrete start-up skills and human capital and engender high growth. Incremental funding of 47% over current levels budgeted to buoy entrepreneurial activity are mandated for Sweden to approach its GEI potential.Originality/valueInsights are derived from extracting data drawn from a new methodology for gauging entrepreneurial activity incorporating individual and institutional variables into a single model that combines PFB and GEI analysis with a view to identifying, through the PFB approach and weak aspects of Sweden's entrepreneurial performance.

COVID-19 management: The vaccination drive in India

ObjectiveWe undertook the study to present a comprehensive overview of COVID-19 related measures, largely centred around the development of vaccination related policies, their implementation and challenges faced in the vaccination drive in India. MethodsA targeted review of literature was conducted to collect relevant data from official government documents, national as well as international databases, media reports and published research articles. The data were summarized to assess Indian government's vaccination campaign and its outcomes as a response to COVID-19 pandemic. ResultsThe five-point strategy adopted by government of India was “COVID appropriate behaviour, test, track, treat and vaccinate”. With respect to vaccination, there have been periodic shifts in the policies in terms of eligible beneficiaries, procurement, and distribution plans, import and export strategy, involvement of private sector and use of technology. The government utilized technology for facilitating vaccination for the beneficiaries and monitoring vaccination coverage. ConclusionThe monopoly of central government in vaccine procurement resulted in bulk orders at low price rates. However, the implementation of liberalized policy led to differential pricing and delayed achievement of set targets. The population preference for free vaccines and low profit margins for the private sector due to price caps resulted in a limited contribution of the dominant private health sector of the country. A wavering pattern was observed in the vaccination coverage, which was related majorly to vaccine availability and hesitancy. The campaign will require consistent monitoring for timely identification of bottlenecks for the lifesaving initiative.

Improving an electric power planning system in the commuter rail passenger complex

The transport industry is an energy intensive one, so power saving measures in transport in general, and railway transport in particular, deserve greater attention. It should be noted that the transport complex has developed a programme of measures aimed at power saving in the industry. Nevertheless, the issue of improving the electric power planning system for the commuter rail complex remains relevant. It is worth noting that the results of theoretical research, supplemented by the results of field-based scientific research, demonstrate the lack of a perfect approach to electric power consumption planning at present. Identification of bottlenecks in the existing electric power planning system is possible with application of general scientific and special methods and techniques, as follows: dialectical, logical, analytical, systemic and functional, comparative, economic and mathematical, a method of scientific abstraction, classification, grouping and comparison, analysis and synthesis, induction and deduction, a graphical method, a method of statistical analysis, together with private methods of economic sciences, providing reliability and objectivity of the scientific conclusions and results obtained. In this article the issue of transition from the existing electric power consumption planning system in the multiple unit rolling stock to the author’s planning system is considered; the evidential basis is presented by an example of the Regional Multiple Unit Rolling Stock Directorate. The proposed planning system provides an opportunity to calculate the standard values of electric power consumption in the multiple unit rolling stock promptly. The authors assert that the advantage of the proposed planning system is its calculation accuracy of one kilowatt consumed, as well as its transparency, resulting not only in the economic component of the Regional Directorate of Multiple Unit Facilities, but also in the passenger service quality. A compliance with the standards presented in this planning system implies a comfortable microclimate in commuter coaches.

A Comparison of Approaches for the Time Series Forecasting of Motorway Traffic Flow Rate at Hourly and Daily Aggregation Levels

Congestion forms a large problem in many major metropolitan regions around the world, leading to delays and societal costs. Congestion is generally associated with reduced average speed at a high traffic flow rate. This traffic flow rate is defined as the number of vehicles that pass a certain location at a given time. The modelling and prediction of this traffic flow rate may lead to valuable insights that may be used to reduce congestion and societal costs. This study aims to predict the traffic flow rate for 41 different locations in and around Amsterdam, The Netherlands. Using TBATS, SARIMAX and LSTM models, among others, the traffic flow rate of these locations has successfully been modelled. These models may provide accurate predictions for the future flow rate, which may be useful for the identification of infrastructure bottlenecks and the scheduling of maintenance. Considering the dramatic effects of the COVID-19 pandemic on the traffic flow rate, the inclusion of 2020 data with a number of external factors, could lead to an improvement of the results and the ability to model the future effects of the pandemic.

Формування системи оцінки якості надання адміністративних послуг

Зазначено, що у сучасній практиці найчастіше використовують розуміння того, що комплексний показник якості має бути представлений як сукупність показників якості послуг і якості обслуговування. Зауважено, що система оцінки якості формує комплекс критеріїв, що охоплює всі можливі сторони, а критеріями є показники, які є підставою для встановлення стандартів надання адміністративних послуг, і за якими можна визначати, наскільки при наданні конкретної послуги є задоволеними потреби та інтереси громадянина та наскільки адекватною і професійною є діяльність адміністративного органу. Визначено, що новітні моделі публічного управління орієнтовані передусім на те, щоб створити гнучку й результативну ринково орієнтовну систему, стратегічно спрямовану на клієнта – громадянина. Відомо, що призначення оцінки якості адміністративних послуг – це підвищення якості самих послуг. Підсумовано, що на зміну адмініструванню має прийти менеджмент із його ідеологією, методологією, передовими підходами та технікою, а оцінка якості надання адміністративних послуг повинна здійснюватися на основі сформованих критеріїв, щоб мати змогу оцінювати та стандартизувати процеси надання цих послуг.

Hospital quality monitoring and evaluation system using linked spreadsheets on Microsoft SharePoint

Background Establishment of a systematic way of measurement and utilization of indicators for improvement is one of the most challenging issues in monitoring and evaluation of indicators in healthcare settings. In realizing these fundamental challenges, we designed a monitoring and evaluation system incorporating a hospital-wide quality variance report (QVR) system using linked Microsoft Excel® spreadsheets on Microsoft SharePoint®. Methods Indicators were determined at the departmental/unit level in line with the institutional goals, departmental functions, quality expectations, inputs/outputs, clinical priorities, compliance to policies/procedures/protocols/guidelines/pathways as well as in response to gaps in service delivery picked during root cause analyses. The sample design was determined in accordance with the characteristics of the population. Drawing of sample units was done using a simple random sampling technique without replacement or systematic random sampling. The indicator’s monitoring was enhanced visually by allocating colour codes based on performance across the months and quarters. The action plan tab consisted of a platform that aids in documenting corrective actions arising from the performance reviews. Results and discussion The QVR reporting system ensured a standardized format of monitoring throughout the institution with a reduced turnaround time from data collection to analysis. Further, continuity of the monitoring and evaluation (M&E) system was guaranteed even if an individual left the institution. The analysis of the QVR allowed hospital-wide trending on cross-cutting indicators with consequent ease of communication to multiple stakeholders. The automation has saved time and increased accuracy which has enhanced credible engagements during quality meetings. Conclusions Use of this system greatly enhanced quality performance monitoring in the hospital, identification of major bottlenecks that warranted hospital-wide projects or departmental-level projects. The QVR system enhanced the efficiency and accuracy of quality monitoring from data collection through to performance reviews. The QVR structure allows for customized development of an M&E database application software.

Debottlenecking Approach Revitalizes Aging Platform by Increasing Production 30%

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 203321, “Integrated Debottlenecking Approach Revitalizes Aging Platform by Increasing Production 30% in Gulf of Mexico,” by Ankur Gandhi, Sara L. McConkey, and Jeremy Kimbrough, SPE, Occidental, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed. Successful identification, evaluation, and management of bottlenecks in a complex offshore production processing system is challenging but can increase daily production significantly. The Constitution platform in the Green Canyon area of the Gulf of Mexico, which was commissioned in 2006 with a nameplate capacity of 70,000 BOPD, is a complex system with four fields in varying stages of development. The complete paper focuses on a multidisciplinary process developed to identify, evaluate, and eliminate interdependent bottlenecks on the platform and its flowline network during a 16-month period; this synopsis details some of these findings. Integrated Process A study and field trial during 2016–17 demonstrated the ability to separate fluids above the design capacity, but the team faced challenges in terms of flow reliability even at lower production rates. Therefore, in 2017, an effort was launched to understand and mitigate this issue. The underlying process used for the effort stemmed from principles of Six Sigma and Gemba walks. The steps of the process, detailed in the complete paper, are as follows: 1. Define 2. Measure and analyze 3. Design 4. Verify and execute 5. Review The process allows the team to see the variance between perception and reality. The results-driven, continuous-improvement approach also increases visibility among leaders, giving them a chance to interact with subject-matter experts (SMEs) and to understand key bottlenecks. Platform Bottlenecks and Responses Reservoir and Subsea Network Deliverability. The rate uplift from the debottlenecking efforts was estimated using a reservoir simulation model that included a fully integrated subsea flow net-work model, which solved the reservoir and flow network equations in the same Newtonian iteration. This type of simulation model particularly is suited for the problem at hand, provided that the reservoir model adequately matches historical well performance and the network model matches historical friction pressure losses as a function of rate. The simulation model predicted that the reservoir should be able to deliver a rate uplift of 30% above the production rate before debottlenecking. Topsides Fluids Processing Debottlenecking: General. The late-life debottlenecking of the platform posed many process engineering challenges, some of which stemmed from the inherent flexibility for which the platform was designed. The multitude of gas paths available led to many viable operating alignments of sources to separators and then separators to compressor stages. One initial exercise for debottlenecking was to develop a matrix of potential future operating modes, which would account for the required operator flexibility, as well as to address compressor downtime and the resulting temporary rerouting of sources. Once this matrix was developed, topsides process simulations were developed for each to identify capacity requirements for each equipment item. As detailed in the complete paper, topsides fluids processes involving the oil-cooling system and oil-system hydraulics were also debottlenecked.

Data-driven dynamic bottleneck detection in complex manufacturing systems

Production (throughput) bottlenecks are the critical stations defining and constraining the overall productivity of a system. Effective and timely identification of bottlenecks provide manufacturers essential decision input to allocate limited maintenance and financial resources for throughput improvement. However, identifying throughput bottleneck in industry is not a trivial task. Bottlenecks are usually non-static (shifting) among stations during production, which requires dynamic bottleneck detection methods. An effective methodology requires proper handling of real-time production data and integration of factory physics knowledge. Traditional data-driven bottleneck detection methods only focus on serial production lines, while most production lines are complex. With careful revision and examination, those methods can hardly meet practical industrial needs. Therefore, this paper proposes a systematic approach for bottleneck detection for complex manufacturing systems with non-serial configurations. It extends a well-recognized bottleneck detection algorithm, “the Turning Point Method”, to complex manufacturing systems by evaluating and proposing appropriate heuristic rules. Several common industrial scenarios are evaluated and addressed in this paper, including closed loop structures, parallel line structures, and rework loop structures. The proposed methodology is demonstrated with a one-year pilot study at an automotive powertrain assembly line with complex manufacturing layouts. The result has shown a successful implementation that greatly improved the bottleneck detection capabilities for this manufacturing system and led to an over 30% gain in Overall Equipment Effectiveness (OEE).

Towards a governance assessment framework for geospatial data: A policy coherence evaluation of the geospatial data policy in Flanders

Abstract. Governance Assessment Frameworks allow the identification of implementation bottlenecks and they can propose answers to the identified challenges. However, no assessment framework has been developed to 1) understand how governance factors can affect the development and use of geospatial data (GD) and 2) to allow comparison across different governance contexts. Previous research proved that GD and governance are highly interrelated. Understanding the relevance of policy coherence, and aiming to address the aforementioned gap, we propose the Coherence Assessment Framework for Geospatial Data (CAFGD). CAFGD objective is to contribute to the GD governance literature from an implementation perspective. CAFGD is based on two existing frameworks: 1) the Framework to Support Institutional Arrangements in Geospatial Information Management (FSIAGIM) (Crompvoets and Ho, 2017, 2019) and 2) the Governance Assessment Tool (GAT) (Bressers et al., 2016a). CAFGD uses as governance dimensions the seven structural instruments of FSIAGIM, classified under the hierarchy, market and network governance approach and uses as evaluative quality coherence from GAT. In order to demonstrate the application of CAFGD, we have selected the region of Flanders in Belgium to analyze its GD policy coherence. Our results conclude that coherence is higher in the instruments related to hierarchy. Therefore, coherence is higher among the public sector actors when comparing with the private sector actors. The relation to this sector corresponds to the market and network instruments.

Risk-oriented simulation of the long logistics supply chains in developing enterprises

The paper defines and solves the urgent problem of research of long logistics supply chains in developing enterprises. Due to the distribution of the production system as well as to the presence of a large number of remote suppliers of materials, raw materials and components supply plans are threatened. Supply disruptions in their turn may affect the plans of the main production resulting in possible fines, economic losses, and disruptions in supply of manufactured articles to the markets of high-tech and science-intensive products. To study threats and vulnerabilities in supply logistics the risk-oriented approach that considers potential threats using past statistics and expert assessments has been proposed. The objective of the paper is to develop a risk-oriented method to study the existing threats and assess their impact on the vulnerabilities of the logistics chains of the distributed production system. Due to the complexity of the problematic logistics task, the study is conducted in three different stages: development of the method to simulate the risks in long supply chains; identification of possible bottlenecks in the transport system of supply logistics; threat simulation and vulnerability analysis in supply logistics. To model the risks, an agent model is used, in which the accumulation of risks is carried out by passing orders in the transport system. To simulate bottlenecks, a simulation event model is used, in which large queues that occur in the transport system are analyzed. A stochastic simulation model is used to model threats and vulnerabilities. The new scientific results are risk-oriented method of long logistics supply chains simulation; simulation of supply logistics threats and vulnerabilities. Mathematical methods used: risk theory; simulation event modeling; agent modeling; queuing theory. The proposed approach as a set of developed simulation models should be used to plan the supply of developing production.

Identification of Enzymatic Bottlenecks for the Aerobic Production of Malate from Glycerol by the Systematic Gene Overexpression of Anaplerotic Enzymes in Escherichia coli.

The biotechnological production of dicarboxylic acids (C4) from renewable carbon sources represents an attractive approach for the provision of these valuable compounds by green chemistry means. Glycerol has become a waste product of the biodiesel industry that serves as a highly reduced carbon source for some microorganisms. Escherichia coli is capable of consuming glycerol to produce succinate under anaerobic fermentation, but with the deletion of some tricarboxylic acid (TCA) cycle genes, it is also able to produce succinate and malate in aerobiosis. In this study, we investigate possible rate-limiting enzymes by overexpressing the C-feeding anaplerotic enzymes Ppc, MaeA, MaeB, and Pck in a mutant that lacks the succinate dehydrogenase (Sdh) enzyme. The overexpression of the TCA enzyme Mdh and the activation of the glyoxylate shunt was also examined. Using this unbiased approach, we found that phosphoenol pyruvate carboxylase (Ppc) overexpression enhances an oxidative pathway that leads to increasing succinate, while phosphoenol pyruvate carboxykinase (Pck) favors a more efficient reductive branch that produces mainly malate, at 57.5% of the theoretical maximum molar yield. The optimization of the culture medium revealed the importance of bicarbonate and pH in the production of malate. An additional mutation of the ppc gene highlights its central role in growth and C4 production.

Efficiency of fishmeal and fish oil processing of different pelagic fish species: Identification of processing steps for potential optimization toward protein production for human consumption

Most fish meal and fish oil production facilities run with outdated processes, producing low-value products, typically not intended for human consumption. The aim of the study was to perform a detailed analysis of the current fishmeal and oil production processes of capelin (Mallotus villosus), and compare the key locations of both fattier and leaner pelagic raw material to identify which steps need to be improved for the production of higher-value products. Results indicated inefficient draining and concentration during the production process and ineffective break-down of the raw material, as lipid separation was ineffective in all studied species. Although the raw material initially differed in lipid content (2%–20%, depending on the species), all fishmeal produced resulted in high-lipid fishmeal (9%–14%). Chemical composition variations in the solid steams entering the dryers suggested that drying these streams individually could lead to more process and product flexibility, which can result in higher-value products, such as fish meal and protein powders for human consumption. Practical applications Traditional production lines of fishmeal and fish oil factories have remained the same for decades, resulting in low-quality products with a low market price. Therefore, optimization and redesign of the production processes are needed to increase the product quality. This study analyzed the lipid quality and water content in all processing steps. The current evaluations will help to shift the traditional fishmeal and fish oil production process from low-quality to high-quality products intended for human consumption by presenting a detailed analysis of the production process not available in the literature to date. Our results can act as reference values for other fishmeal and fish oil producers to assess their production quality. That includes identification of bottlenecks affecting the efficiency and effectiveness of their production processes.

Medicine Shortages: From Assumption to Evidence to Action - A Proposal for Using the FMD Data Repositories for Shortages Monitoring.

Medicine shortages may negatively impact patient care and the patient experience. Shortages should be a priority of industry, supply chain stakeholders and national competent authorities, and deserve more than empathy or “lip-service” but serious engagement and action. Under the overarching principle that without correct measurements in place there cannot be any improvement in overall performance (1), stakeholders in the pharmaceutical supply chain, notably pharmaceutical manufacturers have made the call for all relevant sources of information to be used in order to provide additional intelligence about the root causes and drivers of shortages, including the identification of bottlenecks in the supply chain. This paper outlines a proposal for using the data stored in the interoperable network of national repositories being set up in the context of the Falsified Medicines Directive (Directive 2011/62/EU) and its Delegated Regulation 2016/161/EU on safety features for providing additional intelligence in monitoring shortages. The paper analyses the potential feasibility and readiness of using this data for monitoring shortages as well as the strengths and weaknesses of the approach. We explore also what are some of the other complementary data sources that could be analyzed in conjunction with the data in the repository system to sharpen the overall analysis. Lastly, we provide a theoretical but concrete use case for using the abovementioned data for better informing decisions to prevent and mitigate shortages. In doing so, we explain the interlink between patient needs at country level, demand from economic actors, intra-EU parallel trade and manufacturer-imposed supply quotas and propose a mechanism for collaboration between national competent authorities and supply chain stakeholders for early detection and action to prevent medicine shortages from occurring.

Identification of environmental supply chain bottlenecks: a case study of the Ethiopian healthcare supply chain

PurposeThe increasing rate of environmental concern and awareness by society has attracted attention from researchers and organisations to consider how to proceed towards green supply chains. The purpose of this paper is to identify operational bottlenecks in the multi-tier supply chain to guide organisations towards where to concentrate their efforts to address their supply chain environmental challenges.Design/methodology/approachThis paper presents a literature review identifying green supply chain challenges of multi-tier supply chains. Following the literature review is a case study of the Ethiopian health supply chain with 11 interviews, 11 international and 6 national surveys and data from public health information systems. An analysis based on multi-tier supply chain modelling is used to identify environmental supply chain bottlenecks.FindingsThis research found that the supply chain actors face severe challenges towards enhanced green supply chain performance mainly because of poor inventory management (IN), inefficient tracking and tracing (TR) and fake or sub-standard products in the supply chain, especially counterfeit medicines (CO). Specific environmental bottlenecks within each of the challenge areas IN, TR and CO where identified serving as recommendations for where supply chain actors should focus their work towards greener supply chains.Research limitations/implicationsThe data come from participants in a single country, Ethiopia; although the supply chain challenges are common for developing countries in general.Practical implicationsThis research presents a modelling approach to identify supply chain activities considered as environmental bottlenecks in multi-tier supply chains. The environmental bottlenecks pinpoint supply chain activities to focus on for a transition towards green supply chains for manufacturers, public and private health organisations, hospitals and health care units.Originality/valueThis paper contributes to the literature on GSCM by developing a multi-tier modelling approach for identifying environmental supply chain bottlenecks. The applicability of the model is demonstrated by the identification of environmental bottlenecks in a healthcare supply chain supporting decisions on what challenges a green supply chain strategy should address. It serves as a basis for future research on where to implement GSCM practices in supply chains (SCs).

Applying Process Mining to Analyze the Behavior of Learners in Online Courses

The most critical challenge in analyzing the data of Massive Open Online Courses (MOOC) using process mining techniques is storing event logs in appropriate formats. In this study, an innovative approach for extraction of MOOC data is described. Thereafter, several process-discovery techniques, i.e., Dotted Chart Analysis, Fuzzy Miner, and Social Network Miner, are applied to the extracted MOOC data. In addition, behavioral studies of high- and low-performance students taking online courses are conducted. These studies considered i) overall behavioral statistics, ii) identification of bottlenecks and loopback behavior through frequency- and time-performance-based approaches, and iii) working together relationships. The results indicated that there are significant behavioral differences between the two groups. We expect that the results of this study will help educators understand students’ behavioral patterns and better organize online course content.

Integration of BPMN Modeling and Multi-actor AHP-aided Evaluation to Improve Port Rail Operations

Selecting the best scenario of intervention to improve the functioning of complex systems represents a troublesome task both for public and private decision makers, since it requires the deployment of appropriate analysis and evaluation tools. In the case of intermodal transport systems, complexity is given by the execution of different types of activities using various resources, and by the presence of several actors operating in the same environment with diverse goals. In this paper, an integrated approach to assess design alternatives regarding rail port operations is proposed by combining business process modeling and multi-actor multi-criteria evaluation. In fact, a railway process has been graphically represented by means of the standardized modeling language called Business Process Modeling and Notation (BPMN) at different levels of detail, i.e. taking into account not only the actual transport operations but also the necessary documentary procedures to perform the freight transfer services. In addition to the identification of possible bottlenecks, the analysis of the considered railway process has enabled the determination of its most significant features. These parameters have been subsequently used as some of the criteria according to which the performances of the examined scenarios of intervention have been evaluated, adopting the Analytic Hierarchy Process (AHP) technique. Furthermore, the appraisal has been enhanced by explicitly including the key stakeholders involved in the railway process at hand. The developed methodology has been applied to the case study of the Port of Trieste, Italy, in order to investigate possibilities for an increase in railway capacity.

Understanding and Controlling the Performance-Limiting Steps of Catalyst-Modified Semiconductors.

Understanding and controlling factors that restrict the rates of fuel-forming reactions are essential to designing effective catalyst-modified semiconductors for applications in solar-to-fuel technologies. Herein, we describe GaAs semiconductors featuring a polymeric coating that contains cobaloxime-type catalysts for photoelectrochemically powering hydrogen production. The activities of these electrodes (limiting current densities >20 mA cm-2 under 1-sun illumination) enable identification of fundamental performance-limiting bottlenecks encountered at relatively high rates of fuel formation. Experiments conducted under varying bias potential, pH, illumination intensity, and scan rate reveal two distinct mechanisms of photoelectrochemical hydrogen production. At relatively low polarization and pH, the limiting photoactivity is independent of illumination conditions and is attributed to a mechanism involving reduction of substrate protons. At relatively high polarization or pH, the limiting photoactivity shows a linear response to increasing photon flux and is attributed to a mechanism involving reduction of substrate water. This work illustrates the complex interplay between transport of photons, electrons, and chemical substrates in photoelectrosynthetic reactions and highlights diagnostic tools for better understanding these processes.

CAMP: cost-aware multiparty session protocols

This paper presents CAMP, a new static performance analysis framework for message-passing concurrent and distributed systems, based on the theory of multiparty session types (MPST). Understanding the run-time performance of concurrent and distributed systems is of great importance for the identification of bottlenecks and optimisation opportunities. In the message-passing setting, these bottlenecks are generally communication overheads and synchronisation times. Despite its importance, reasoning about these intensional properties of software, such as performance, has received little attention, compared to verifying extensional properties, such as correctness. Behavioural protocol specifications based on sessions types capture not only extensional, but also intensional properties of concurrent and distributed systems. CAMP augments MPST with annotations of communication latency and local computation cost, defined as estimated execution times, that we use to extract cost equations from protocol descriptions. CAMP is also extendable to analyse asynchronous communication optimisation built on a recent advance of session type theories. We apply our tool to different existing benchmarks and use cases in the literature with a wide range of communication protocols, implemented in C, MPI-C, Scala, Go, and OCaml. Our benchmarks show that, in most of the cases, we predict an upper-bound on the real execution costs with < 15% error.