System Designers Research Articles

Evaluating the Impact of Weather Conditions on the Effectiveness and Performance of PV Solar Systems and Inverters

Solar photovoltaic (PV) systems have become an increasingly popular and environmentally friendly source of renewable energy. However, the performance and effectiveness of these systems can be significantly influenced by various weather conditions. This paper aims to evaluate the impact of weather conditions on the effectiveness and performance of PV solar systems and inverters. This paper utilizes a comprehensive dataset of solar irradiance, temperature, wind speed, and other weather parameters collected from multiple locations over an extended period. Various performance indicators, such as power output, efficiency, and reliability, are analyzed and compared under different weather conditions. The findings of this paper reveal the significant influence of weather conditions on the performance of PV solar systems and inverters. It is observed that variations in solar irradiance, temperature can lead to fluctuations in power output and efficiency. High ambient temperatures, for example, can negatively affect the performance of solar panels by increasing the operating temperature and reducing their conversion efficiency. These events can cause physical damage, reduce solar irradiance, and impair the functionality of inverters, leading to a decrease in overall system performance. The research outcomes presented in this paper provide valuable insights for system designers, engineers, policymakers, and investors in the renewable energy sector.

An Influence of Parameters of the Control Signal of Power LEDs on Their Junction Temperature and Emitted Light

This article presents the method of implementation and the results of experimental investigations illustrating an influence of parameters of the signal controlling the current flowing through power LEDs on their junction temperature and on parameters characterizing the light emitted by them. The measurement system used and the tested power LEDs are described. The results of measurements of the junction temperature of the tested devices, the values of the average value of the power dissipated in the tested devices and the photometric and radiometric parameters of these devices obtained for different values of frequency and the duty cycle of the signal controlling the current flowing through the tested diodes are presented and discussed. It is shown that the operation of the considered semiconductor devices is more effective at low frequency values. The possibility of adjusting the optical parameters of the power LEDs in the considered range of frequency and the duty cycle adjustment is assessed. Additionally, the measured waveforms of the current supplying the tested LEDs is shown. The influence of the parasitic capacitances of the tested devices is discussed. On the basis of the obtained investigation results, some recommendations for the designers of lighting systems can be formulated. In order to obtain an almost linear dependence of the illuminance on the duty cycle, the values of frequency not exceeding 10 kHz should be used.

Analysis of E-Learning System Use Using Combined TAM and ECT Factors

The use of e-learning systems has become widespread in higher education institutions in Oman. However, understanding of factors that influence student acceptance and usage of these systems is lacking. This study combined the factors of the Technology Acceptance Model (TAM) and Expectation–Confirmation Theory (ECT) to examine the acceptance and use of e-learning systems by students in Omani HEIs. A survey was conducted with 220 students from Al-Buraimi University College in Oman to collect data on perceived usefulness, perceived ease of use, behavioral intention, and e-learning system use. A model was created by merging eight interactions between TAM, ECT, and seven variables. The results showed that perceived usefulness and ease of use were significant predictors of students’ intention to use e-learning systems, and behavioral intention had a direct effect on the actual use of e-learning systems. These findings provide valuable insights for e-learning system designers, developers, and educators in Oman and similar contexts to design and implement e-learning systems that meet student needs and expectations.

The Study of Surface Vessel Integrated Underwater Defence Effectiveness Evaluation on newly Decision-centric warfare

Surface vessels face the multi-level targets form air, surface and underwater. Due to the complex characteristics, the underwater targets draw the special focus of weapon system and tactics designer. Facing the severe challenge which carried out by the underwater weapon technology to the underwater defense system software, the paper analyze the elements which effect the underwater defense operation, characteristics and strategy of integration of typical soft countermeasure and hard killing weapon, the paper put forward the underwater defense effectiveness evaluation index system, emulation evaluation methods, so as to improve the current technology from the perspectives of functionally and utility.

META-GLARE: A Computer-Interpretable Guideline System Shell

Computer-interpretable Guideline (CIG) systems are important tools for ensuring healthcare practice quality and standardization. They usually provide a tool to acquire CIGs, and one to execute them on specific patients. Current CIG systems rely on their own formalism to represent clinical guidelines, so moving to new phenomena/domains may require substantial extensions. We propose an innovative approach, providing a “shell” that facilitates system designers to define new CIG systems (or to update an existing one) through the definition of a new CIG representation formalism, based on the Task-Network model. We based it on our previous work on META-GLARE, and we extend it with a general execution tool, able to operate on any CIG representation formalism acquired through the META-GLARE acquisition tool. Developed with modularity and compositionality principles, the tool exploits an open library of basic execution methods. It offers a general execution mechanism supporting various CIG formalisms. We successfully applied our approach to three practical case studies. We have identified a reference CIG formalism (the one currently supported by the META-GLARE library) and compared its expressiveness to benchmark approaches. META-GLARE constitutes the first shell in the literature to facilitate the (formalism-based) design and development of CIG systems, considering both acquisition and execution.

Applying a participatory systems and value approach in a transdisciplinary exercise: on assessing the impact of training and education initiatives

ABSTRACT Participatory systems approaches are readily used in multi- and inter-disciplinary exploration of shared processes, but are less-commonly applied in trans-disciplinary efforts eliciting principles that generalise across contexts. The authors were charged with developing a transdisciplinary framework for prospectively or retrospectively assessing initiatives to improve education and training within a multifaceted organisation. A common System Impact Model (SIM) was developed in a series of workshops involving thirty participants from different disciplines, clinical specialisms, and organisations. The model provided a greater understanding of the interrelationships between factors influencing the benefits of education and training and development as seen from various stakeholder perspectives. It was used to create a system for assessing the impact of initiatives on service-users/patients, trainees, and organisations. It was shown to enable a range of participants to connect on common challenges, to maximise cross-, multi-, and inter-disciplinary learning, and to uncover new strategies for delivering value, as system designers.

Performance of the modified clock skew estimator and its upper bound for the IEEE 1588v2 (PTP) case under packet loss and fractional Gaussian noise environment

Precision Time Protocol (PTP) is a time protocol based on the Master and Slave exchanging messages with time stamps. In practical PTP systems, we have packet loss, a phenomenon where some of the PTP messages get lost in the Network. Packet loss may reduce the performance of the clock skew estimator from the mean square error (MSE) perspective. Recently, the same authors presented simulation results that show the clock skew performance of the three clock skew estimators (the two-way delay (TWD) clock skew estimator and the one-way delay (OWD) clock skew estimator for the Forward and Reverse paths) under the packet loss case in the fractional Gaussian noise (fGn) environment with Hurst exponent parameter (H) in the range of 0.5 ≤ H < 1, where indeed the clock skew performance was degraded compared to the non-packet loss case. Please note that for 0.5 < H < 1, the corresponding fGn is of long-range dependency (LRD). This paper proposes an algorithm that estimates the missing timestamps in the packet loss and fGn (0.5 ≤ H < 1) case. We use those estimates to generate three modified clock skew estimators (the two-way delay (TWD) modified clock skew estimator and the one-way delay (OWD) modified clock skew estimator for the Forward and Reverse paths) applicable to the packet loss, non-packet loss, and fGn (0.5 ≤ H < 1) case based on the same authors’ previously developed clock skew estimators. Those modified clock skew estimators led, based on simulation results, to an improved clock skew performance in the packet loss and fGn (0.5 ≤ H < 1) case compared with the authors’ previously developed clock skew estimators and those known from the literature (the ML-like (MLLE) and Kalman clock skew estimators). With the MSE expression, the system designer can know how many Sync periods are needed for the clock skew synchronization task to reach the system’s requirements from the MSE perspective. But no MSE expression exists in the literature for the packet loss case. In this paper, we derive closed-form approximated expressions for the MSE upper bounds related to the modified TWD and OWD clock skew estimators valid for the packet loss and fGn (0.5 ≤ H < 1) cases.

Integrated personal health record (PHR) security: requirements and mechanisms

BackgroundPersonal Health Records (PHRs) are designed to fulfill the goals of electronic health (eHealth) and empower the individual in the process of self-care. Integrated PHR can improve the quality of care, strengthen the patient-healthcare provider relationship, and reduce healthcare costs. Still, the process of PHR acceptance and use has been slow and mainly hindered by people’s concerns about the security of their personal health information. Thus, the present study aimed to identify the Integrated PHR security requirements and mechanisms.MethodsIn this applied study, PHR security requirements were identified with a literature review of (library sources, research articles, scientific documents, and reliable websites). The identified requirements were classified, and a questionnaire was developed accordingly. Thirty experts completed the questionnaire in a two-round Delphi technique, and the data were analyzed by descriptive statistics.ResultsThe PHR security requirements were identified and classified into seven dimensions confidentiality, availability, integrity, authentication, authorization, non-repudiation, and right of access, each dimension having certain mechanisms. On average, the experts reached an agreement about the mechanisms of confidentiality (94.67%), availability (96.67%), integrity (93.33%), authentication (100%), authorization (97.78%), non-repudiation (100%), and right of access (90%).ConclusionIntegrated PHR security is a requirement for its acceptance and use. To design a useful and reliable integrated PHR, system designers, health policymakers, and healthcare organizations must identify and apply security requirements to guarantee the privacy and confidentiality of data.

Practical ethical frameworks for civil engineering and environmental systems

ABSTRACT Ethics is receiving increased emphasis in civil and environmental engineering. However, despite the proliferation of college textbooks and courses encouraging ethical reasoning, engineers in practice often limit their understanding narrowly to their individual actions. Broader issues of global importance are usually addressed in an ad-hoc manner, if at all. Our goal is to present the topic of ethics in a way that appeals to engineers, especially those receptive to ‘systems thinking’. Our broader motivation is to encourage the development of educated, virtuous and caring professionals who engage in contextual ethical reasoning about complex systems. To these ends, we summarise relevant theoretical and applied concepts for ethical analysis, building from a recent chapter that reflects on ethics from an engineering systems perspective (but applied to the healthcare industry). We emphasise virtue ethics and the ethics of care as crucial supplements to duty ethics and utilitarianism. Analytical methods we discuss include Value Sensitive Design, Design for Care, and a multi-level classification of ethical issues into the micro (individual), meso (institutional), and macro (societal) levels. This work collects relevant considerations for designers of civil and environmental engineering systems and researchers interested in developing related design and analysis methods that include practical ethical reasoning. This work is part of a Special Issue on Systems Perspectives: Clarity through Examples (see Dias 2023).

Model‐based Framework for Data and Knowledge‐Driven Systems Architecting Demonstrated on a Hydrogen‐Powered Concept Aircraft

AbstractAircraft development is a protracted process over many years. Novel concept aircraft with new energy sources and disruptive systems technologies are investigated during the aircraft conceptual design phase with the goal to achieve sustainable aviation. Current development cycles need to be accelerated to reduce time to market and development costs of novel aircraft, while still handling complexity and uncertainty of systems technologies. Therefore, a holistic framework for knowledge‐based systems architecting using a model‐based systems engineering approach is presented. This framework has the purpose to conserve and provide knowledge, i.e., information, data, and experiences about existing systems architectures, to the engineer. The developed framework consists of a database concept, a method for model‐based systems architecting, and an interface to the overall systems design software toolGeneSys. Based on evaluating different modeling languages and tools,MathWorks System Composeris selected as most suitable tool for knowledge‐based systems architecting. The developed framework is then demonstrated by conserving and reusing formalized knowledge for the design of a novel hydrogen‐powered concept aircraft. On‐board systems architecture models are saved in a database and automatically recreated reducing development time. The complete graphical representation could not yet be stored in a formalized manner partly reducing the advantage of a clear representation of model‐based systems architecting. However, this did not reduce automatic recreation and evaluation capabilities.

Architecting Digital Engineering Requirements for Risk Management & Systems Architecting

AbstractThis paper describes the risk management and system architecting digital thread within Digital Engineering (DE). It uses a systems engineering methodology that begins at source processes and ultimately provides component‐level requirements that software tools will need to satisfy to provide the risk management and system architecting digital thread capability. The risk management and system architecting digital thread is analyzed throughout each step of the systems engineering methodology. The methodology used is also presented as a way other DE digital threads can be analyzed from source processes to component‐level requirements.

Understanding Security in Smart City Domains From the ANT-Centric Perspective

A city is a large human settlement that serves the people who live there, and a smart city is a concept of how cities might better serve their residents through new forms of technology. In this paper, we focus on four major smart city domains according to Maslow’s hierarchy of needs: smart utility, smart transportation, smart homes, and smart healthcare. Numerous IoT applications have been developed to achieve the intelligence that we desire in our smart domains, ranging from personal gadgets such as health trackers and smart watches to large-scale industrial IoT systems such as nuclear and energy management systems. However, many of the existing smart city IoT solutions can be made better by considering the suitability of their security strategies. Inappropriate system security designs generally occur in two scenarios: first, system designers recognize the importance of security but are unsure of where, when, or how to implement it; and second, system designers try to fit traditional security designs to meet the smart city security context. Thus, the objective of this paper is to provide application designers with the missing security link they may need in order to improve their security designs. By evaluating the specific context of each smart city domain and the context-specific security requirements, we aim to provide directions on when, where, and how they should implement security strategies and the possible security challenges they need to consider. In addition, we present a new perspective on security issues in smart cities from a data-centric viewpoint by referring to the reference architecture, the Activity-Network-Things (ANT)-centric architecture. This architecture is built upon the concept of “security in a zero-trust environment", to achieve end-to-end data security. By doing so, we reduce the security risks posed by new system interactions or unanticipated user behaviors while avoiding the hassle of regularly upgrading security models.

Architecting Descriptive Models for MBSE

AbstractModel‐Based Systems Engineering (MBSE) is becoming increasingly recognized as a critical enabler for significantly improving the effectiveness and efficiency of systems engineering. While MBSE is seeing significant growth in its application to complex system development programs, the growth of MBSE adoption and realized value is often stymied by the growth of technical debt in the descriptive models that serve as the foundation of knowledge capture and communication in an MBSE environment. Just as a good system architect or software architect makes key decisions early in the life of a system or software product to maximize the likelihood of stakeholder satisfaction throughout its life, a good model architect can provide that same invaluable function for descriptive models. The methods and practices of system and software architecting can be readily adapted to address the technical debt growth problem often seen in the development of descriptive models. This paper describes the emerging discipline of “model architecting,” comparing and contrasting it with system and software architecting practices. The paper describes a representative set of model architecting patterns that illustrate model architecting principles, then identifies some of the key roles, responsibilities, and competencies required of the model architect.

Quantifying the energetic cost tradeoffs of photovoltaic pumping systems for Sub-Saharan African smallholder farms

As solar technology has matured, irrigation using photovoltaic pumping systems (PVPSs) has gained popularity in developing markets as an effective means to alleviate poverty and increase food security. Yet, there remains a barrier to adoption; the upfront costs of PVPSs pose a financial burden for many low-income farmers. In a PVPS, the capital cost of the solar array contributes a large portion of upfront system costs. The solar pump is the largest energy consumer in the system, thus its efficiency directly impacts the size and cost of the solar array. There is a limited quantitative understanding of how solar pump efficiency affects the capital cost of the solar array. This study presents a technoeconomic framework to directly quantify the impact of solar pump efficiency on the cost of the solar array in a PVPS, for a range of hydraulic operating conditions. New empirical efficiency scaling laws were created by characterizing the efficiencies of 4-inch multistage centrifugal borehole pumps and induction motors. The utility of the technoeconomic framework is demonstrated through a case study comparing solar pump architectures with motors of different efficiencies. Results indicate that, despite the increased motor cost, the use of high-efficiency motors in solar pumps may lead to an overall cost reduction in a PVPS. Counter to the conventional capital cost-driven process, this work demonstrates that an efficiency-driven design process could improve low-cost, solar-powered system design. Engineers and system designers can leverage the presented framework during the design process to make informed decisions to achieve more cost-effective PVPSs.

Elder People and Personal Data: New Challenges in Health Platformization

In Uruguay, as in many countries around the world, healthcare providers are looking to digital technologies to enhance service provision. This includes introducing new data-intensive systems that facilitate connections between healthcare providers and patients and maintaining records of these interactions. This article considers the numeric ability of older citizens to critically assess the implications of platformization and datafication within the Uruguayan healthcare system with a view to identifying implications for digital literacy programs. The ability of older people to manage their personal data within healthcare systems shapes their ability to enact citizenship and human rights. This reality came into sharp relief during the recent Covid-19 pandemic, demonstrating the extent to which core social services have become datafied and digitally mediated, as well as their potential to deepen digital divides where senior citizens are concerned. Critical perspectives on technological change, well-being, and ageing offer useful perspectives on this challenge. Drawing inspiration from these perspectives, in this article, we explore the results of a digital literacy initiative that worked with 16 seniors to explore their experiences of personal data collection within Uruguay’s new National Comprehensive Health System. Our approach simultaneously worked to build digital literacy while also revealing the complex relationships and disconnections between the ontological frameworks mapped onto healthcare by systems designers and the reality of older people. In the conclusions, we consider the implications of these observations for seniors’ digital literacy interventions that foster seniors’ critical understanding of their data subjectivity in the context of local healthcare systems.

Using credible failure rates for SIS ensures process safety: A summary of the panel discussion

AbstractOn March 13, 2023, in conjunction with the 19th Global Congress on Process Safety, four of the authors gathered to participate in a panel session. The discussion centered on the premise that many individual device failure rates published by some manufacturers and some certifying agencies are deemed—by members of the panel, many safety instrumented system (SIS) designers, and practicing engineers in the field—to be too low. This is especially true for mechanical final elements. A SIS designed using these unrealistic failure rates often results in estimated safety integrity levels (SILs) for the individual safety instrumented functions (SIFs) comprising the SIS, which would be achievable only under the most optimistic assumptions regarding installation, operation, and maintenance. These estimated SILs are unlikely to be achieved in the field. The panel discussed the underlying causes of this serious safety issue and proposed some possible solutions. This paper summarizes the panel discussion among four of the authors. Relevant graphics shown during the discussion and some panelists' quotations are included.

The interactive effect of organizational identification and reward type on reward valuation

AbstractRecent management trends highlight two techniques firms use to motivate employee effort: (1) fostering employees' organizational identification (OI) and (2) offering employees tangible rewards such as gift cards instead of cash rewards. We use three studies to examine how OI affects employees' reward valuation and how such effects differ depending on the reward type. Study 1 is an experiment, demonstrating that increasing OI increases the emphasis participants place on a reward's symbolic value, which then increases the total value of the reward—to a larger extent when the reward is tangible than when it is cash. Study 2 is an experiment, providing evidence that Study 1 results are robust to using a tangible reward that is not socially consumed, that is selected either by the firm or by the employee, and that is either a good or poor fit with the employee's personal preference. Finally, Study 3 is a survey, asking respondents about actual rewards they received from their current employer and capturing their actual OI with their current employer. Results in Study 3 are inferentially similar to those in Study 1 and Study 2, albeit stronger for rewards of smaller monetary value. Collectively, these results highlight the particular benefit of strong OI on how employees value tangible rewards relative to cash rewards, which should be of interest to incentive system designers.

A tri-level optimization model for facility location-protection problem considering design and redesign decisions under disruption

PurposeFortification-interdiction models provide system designers with a broader perspective to identify and protect vital components. Based on this concept, the authors examine how disruptions impact critical supply systems and propose the most effective protection strategies based on three levels of decision-makers. This paper aims to investigate location and fortification decisions at the first level. Moreover, a redesign problem is presented in the third level to locate backup facilities and reallocate undisrupted facilities following the realization of the disruptive agent decisions at the second level.Design/methodology/approachTo address this problem, the authors develop a tri-level planner-attacker-defender optimization model. The model minimizes investment and demand satisfaction costs and alleviates maximal post-disruption costs. While decisions are decentralized at different levels, the authors develop an integrated solution algorithm to solve the model using the column-and-constraint generation (CCG) method.FindingsThe model and the solution approach are tested on a real supply system consisting of several hospitals and demand areas in a region in Iran. Results indicate that incorporating redesign decisions at the third level reduces maximum disruption costs.Originality/valueThe paper makes the following contributions: presenting a novel tri-level optimization model to formulate facility location and interdiction problems simultaneously, considering corrective measures at the third level to reconfigure the system after interdiction, creating a resilient supply system that can fulfill all demands after disruptions, employing a nested CCG method to solve the model.

Comparative Analysis of Type-1 and Type-2 Fuzzy Controllers: Exploiting Synergies for Improved Control System Performance

The utilization of fuzzy controllers in control systems has gained significant attention in various fields due to their ability to handle complex and uncertain systems. This paper focuses on comparing the performance of two types of fuzzy controllers: type-1 fuzzy controller and type-2 fuzzy controller. While type-1 fuzzy controllers have been widely studied and applied, the advantages of type-2 fuzzy controllers in dealing with uncertain and ill-defined systems have garnered attention. A thorough analysis and comparison are conducted to investigate the practical benefits of type-2 fuzzy controllers. The study includes an overview of type-1 and type-2 fuzzy sets, followed by the design methodology for the two controllers. The designed controllers are implemented practically, and the results are analyzed and discussed. Previous research studies have shown the potential of type-2 fuzzy controllers to achieve superior performance compared to type-1 controllers. This paper contributes to the existing body of knowledge by presenting empirical evidence and practical insights into the performance of type-2 fuzzy controllers in real-world applications. The findings shed light on the benefits and limitations of utilizing type-2 fuzzy controllers, particularly in scenarios where system knowledge is limited or incomplete. The results of this study provide valuable guidance for control system designers and practitioners in selecting the most appropriate controller for their specific applications. Furthermore, the insights gained from this research contribute to the ongoing exploration and development of fuzzy control systems, enhancing their effectiveness in various domains.

INVESTIGATING THE EXPERIENCES OF STUDENTS WITH DISABILITIES WITH E-LEARNING DURING THE COVID-19 PANDEMIC IN VIETNAMESE HIGHER EDUCATION

This study uses a mixed-methods approach to investigate the experiences of Vietnamese university students with disabilities (visual/mobility impairments) with e-learning as a consequence of emergency remote teaching during the COVID-19 pandemic. An analysis of the ideas of 20 surveyed students with disabilities at eight universities in Ho Chi Minh City and six students interviewed afterward shows that students can change their study habits to adapt to e-learning and to enjoy this model of learning. However, the participants revealed that they also want to experience face-to-face learning so that they can interact with their lecturers and peers more effectively and in more diverse ways, as well as assimilate lectures more easily. Furthermore, the research shows that various adjustments should be made by system designers, universities, and lecturers to make e-learning friendlier to disabled students. The recommended adjustments include designing easy-to-use learning tools and platforms, providing lecturers with the necessary tools and facilities to design lessons appropriate for all students, providing psychological and technical support for disabled students, choosing user-friendly learning applications and platforms, providing students with suitable learning resources, and modifying testing and assessment methods.