Modeling Maintenance Productivity Measurement of Engineering Production Systems: Discrete Event Simulation Approach

Modeling and simulation of industrial information communication systems and networks is one of the major concerns of productivity engineers for the establishment of productivity standards in virtually all functional areas of an industrial organization. Maintenance function is one of such areas that have always engaged the attention of engineering productivity practitioners. However, one of the basic prob- lems is the difficulty in setting up integrated but easy and practical measurement schemes. Even where the measures are set up, the approaches to measurement sometimes are conflicting. Therefore the need for an integrated approach to optimize the basket of parameters measured remains. In this chapter the author attempts to identify approaches in integrated and systematic maintenance productivity measurement and create models for optimising total productivity in maintenance systems. Visual yardstick, utility, queuing systems and simulations approaches for measurement of maintenance productivity are all discussed with a particular focus on markov chain approach for stochastic break- downs in repairable systems.. The chapter also shows how understanding the impact of plant failure and repair/service distributions assists in providing measures for maintenance productivity using discrete event system simulation

Editorial: Recent Advances in Plant Genetic Engineering and Innovative Applications

Plant genetic engineering is one of the most popular advances in plant science that has been included in the mainstream societal discussion (Mackelprang and Lemaux, 2020). This is born out of multiple unresolved debates on genetically modified organisms (GMOs), the involvement of policymakers in an attempt to regulate and ensure its safe application to food crop production and also featuring as a topic in the politics of global aid (Steinwand and Ronald, 2020). Apart from the GMO debate, however, several advances in genetic engineering have been recorded that empower plant scientists to investigate and solve problems previously untouched (Evanega et al., 2022). From the challenge of transforming recalcitrant species and the development of genetic engineering techniques suitable to non-angiosperms to the development of novel genetic engineering technologies and updates to existing technologies, the field of plant genetic engineering is growing and extending the limits of possibilities in Plant Sciences (Zhang et al., 2019). The extension of plant science research capabilities is particularly important as Plant Science has a significant role in global hot topics such as climate change and sustainability. The goal of this research topic is to highlight studies that embody these advances in new biotechnological tools (NBTs) development and the innovative applications of plant genetic engineering. Studies that focus on NBTs development for recalcitrant or previous non-transformable species to allow the unlocking of the biology of these species are of significant interest to this collection. Furthermore, application of novel strategies of next-generation genetic engineering technologies such as genome/gene editing and protein-domain specific technology (e.g., K-Domain technology) (Song and Han, 2021) and innovative applications as well as updates on well-established genetic engineering technologies (e.g., plant artificial minichromosomes and virus-induced silencing) (Yu et al., 2016;Courdavault et al., 2020) will be explored in this collection. Finally, the innovative combination of artificial intelligence or machine learning with genetic engineering to investigate (Alley et al., 2020), solve problems and innovate in plant science is sought after for this collection. Genome Editing and Transgenic Plant Technology Transgenic plant expression of pesticidal proteins derived from Bacillus thuringiensis (Bt) and other bacteria has been successfully used for insect pest control. In a paper by Seyed Ali Ravanfar et al., (https://www.frontiersin.org/articles/10.3389/fpls.2022.899624/full), transgenic curry tree (Bergera koenigii) was produced by expressing the pesticidal protein Cry1Ba1 derived from Bacillus thuringiensis. Interestingly, this transgenic can be produced for potential use as trap plants for suppression of Asian citrus psyllid (Diaphorina citri) populations toward the protection of citrus groves from citrus greening. Another application of using transgenic plants utilizing the K-domain technology to increase maize yield was presented by Guo-Qing Song and Xue Han (https://www.frontiersin.org/articles/10.3389/fpls.2021.664983/full). Keratin-like (K) domain is a conserved protein domain of tens of MIKC-type MADS-box genes in plants. K-domain technology utilizes the expression of the K-domain of a blueberry SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 to regulate plant growth and resulted in grain yield increase by 13 to 100% under different experimental conditions. This K-domain technology opens a new approach to increasing crop yield by its potential of mimicking the K-domains of multiple MADS-box genes. Non-transgenic crop breeding with high production in diverse plants presented by virus-induced gene silencing (VIGS) genetic tools in plants. VIGS exploits an RNA-mediated antiviral defense mechanism [post-transcriptional gene silencing (PTGS)] for functional gene analysis to fulfill some of this promise in diverse aspects. The plant's natural defense mechanism is induced by a virus infection, and some endogenous genes that are homologous to viral genomes could also be silenced at the same time. Modification of the viral genome into a recombinant viral vector containing sequences homologous to host genes causes homologous silencing of endogenous genes in plants. The review by Gongyao Shi et al., (https://www.frontiersin.org/articles/10.3389/fpls.2021.671091/full) summarizes the recent applications in diverse plant species, thus providing a better understanding and advice for functional gene analysis related to crop improvements. As viral vector construction of tobacco rattle virus (TRV) is an important factor of an efficient VIGS system, many modifications have been done based on the original TRV vector to obtain better silencing efficiency in different species. The development of the VIGS system is strongly affected by the selection of Agrobacterium strain, inoculum concentration, environmental factors and proper positive controls. All improvements to VIGS technology will speed up the application of this tool for identifying candidate genes involved in various aspects of plant biology), including plant-environment interactions, plant growth and development, metabolic processes, and other cellular processes in plants. The Brome mosaic virus (BMV)-based VIGS vector was the establishment of a simple and effective VIGS procedure by Yongqin Wang et al., (https://www.frontiersin.org/articles/10.3389/fpls.2021.685187/full) in bread wheat genes PHYTOENE DESATURASE (TaPDS) and PHOSPHATE2 (TaPHO2) as targets. Smaller inserts (~100 nucleotides) were more stable and conferred higher silencing efficiency and longer silencing duration, compared with larger inserts. This VIGS genetic technology has a high potential for a rapid and effective functional genomics tool for high-throughput gene function studies in aerial and root tissues and many plant species. The application of CRISPR/Cas9 was used for efficient multi-site genome editing in coniferous species (Picea glauca) by Ying Cui et al., (https://www.frontiersin.org/articles/10.3389/fpls.2021.751891/full) for target traits modification needed to speed up breeding. This CRISPR/Cas9 system based on somatic embryogenesis was proven for conifers and was optimized based on codon bias in white spruce and a spruce U6 promoter. This conifer-specific CRISPR/Cas9 system was used for multi-site genome editing to target the gene encodes 1-deoxyxylulose 5-phosphate synthase of white spruce by Agrobacterium-mediated transformation and is valuable in gene function research and trait improvement. Establishment of Transgenic Root in Agrobacterium-mediated Gene Transformation The optimization of plant in vitro studies, by considering all the influential factors, is laborious, time-consuming, and challenging because of its multifactorial nature. The developed protocols are based on the model for efficiency in predicting the gene transformation efficiency of plants with a low rate of transformation. The multilayer perceptron topology of an artificial neural network (ANN) was applied to create two predictor models in Agrobacterium-mediated gene transformation of tobacco by Gniewko Niedbała (https://www.frontiersin.org/articles/10.3389/fpls.2021.695110/full). Through the precise and efficient data interpretation, ANN could help optimize the gene transformation conditions in Agrobacterium-mediated gene transformation studies. The study of Vy Nguyen and Iain R. Searle (https://www.frontiersin.org/articles/10.3389/fpls.2021.781014/full) developed a simple, efficient and rapid hairy root transformation system for common vetch to facilitate functional gene analysis. Authors show that the infection of the hypocotyls on 5-day-old in vitro or in vivo, soil-grown seedlings with Rhizobium rhizogenes using a stabbing method on vetch explants was effective to produce transgenic in shoot and hypocotyl-epicotyl explants. This simple method also produces contaminant-free transgenic hairy roots for downstream study and shoots could be helpful in plant propagation. Artificial Minichromosomes Technology Artificial minichromosomes are the next-generation technology for plant genetic engineering and represent an independent platform for expressing foreign genes and the tools for studying the structure and function of chromosomes. This technology for telomere-associated chromosome truncation has been applied successfully in mammals and plants and used as an independent platform for stacking multiple foreign genes without gene segregation. The truncated minichromosome was employed as a platform to receive foreign genes in Brassica napus by Xiangzhen Yin et al. (https://www.frontiersin.org/articles/10.3389/fpls.2021.743792/full). This research primarily focused on the development of stably inherited minichromosomes and their precise characterization and tracking over different generations. A 0.35-kb direct repeat of the Arabidopsis telomeric sequence was transformed into Brassica napus to produce artificial minichromosomes, which were analyzed by multifluorescence in situ hybridization (multi-FISH), genome resequencing, and insertion site-specific PCR, primer extension telomere rapid amplification (PETRA). In summary, the research collected on this Research Topic advances in next generation sequencing and gene editing technologies have revolutionized plant science research that empowers plant biotechnologists to manipulate target gene(s) more precisely and effectively in genetic engineering. We believe that a breakthrough in plant genetic engineering is being made and is going to drive a second Green Revolution that is the key to feeding our future.Non peer reviewe

On relating functional modeling approaches: abstracting functional models from behavioral models

This paper presents a survey of functional modeling approaches and describes a strategy to establish functional knowledge exchange between them. This survey is focused on a comparison of function meanings and representations. It is argued that functions represented as input-output flow transformations correspond to behaviors in the approaches that characterize functions as intended behaviors. Based on this result a strategy is presented to relate the different meanings of function between the approaches, establishing functional knowledge exchange between them. It is shown that this strategy is able to preserve more functional information than the functional knowledge exchange methodology of Kitamura, Mizoguchi, and co-workers. The strategy proposed here consists of two steps. In step one, operation-on-flow functions are translated into behaviors. In step two, intended behavior functions are derived from behaviors. The two-step strategy and its benefits are demonstrated by relating functional models of a power screwdriver between methodologies

Some Findings Concerning Requirements in Agile Methodologies

gile methods have appeared as an attractive alternative to conventional methodologies. These methods try to reduce the time to market and, indirectly, the cost of the product through flexible development and deep customer involvement. The processes related to requirements have been extensively studied in literature, in most cases in the frame of conventional methods. However, conclusions of conventional methodologies could not be necessarily valid for Agile; in some issues, conventional and Agile processes are radically different. As recent surveys report, inadequate project requirements is one of the most conflictive issues in agile approaches and better understanding about this is needed. This paper describes some findings concerning requirements activities in a project developed under an agile methodology. The project intended to evolve an existing product and, therefore, some background information was available. The major difficulties encountered were related to non-functional needs and management of requirements dependencies

Process Performance Analysis in Large-Scale Systems Integrating Different Sources of Information

Process auditing using historical data can identify causes for poor performance and reveal opportunities to improve process operation. To date, the data used has been limited to process measurements; however other sources hold complementary information about the process behavior. This paper proposes a new approach to root-cause diagnosis, which also takes advantage of the information in utility, mechanical and electrical data, alarms and diagrams. Its benefit is demonstrated in an industrial case study, by tackling an important challenge in root-cause analysis: large-scale systems. This paper also defines specifications for a semi-automated tool to implement the proposed approach. © 2012 IFAC

Resilience of New Zealand indigenous forest fragments to impacts of livestock and pest mammals

A number of factors have combined to diminish ecosystem integrity in New Zealand indigenous lowland forest fragments surrounded by intensively grazed pasture. Livestock grazing, mammalian pests, adventive weeds and altered nutrient input regimes are important drivers compounding the changes in fragment structure and function due to historical deforestation and fragmentation. We used qualitative systems modelling and empirical data from Beilschmiedia tawa dominated lowland forest fragments in the Waikato Region to explore the relevance of two common resilience paradigms – engineering resilience and ecological resilience – for addressing the conservation management of forest fragments into the future. Grazing by livestock and foraging/predation by introduced mammalian pests both have direct detrimental impacts on key structural and functional attributes of forest fragments. Release from these perturbations through fencing and pest control leads to partial or full recovery of some key indicators (i.e. increased indigenous plant regeneration and cover, increased invertebrate populations and litter mass, decreased soil fertility and increased nesting success) relative to levels seen in larger forest systems over a range of timescales. These changes indicate that forest fragments do show resilience consistent with adopting an engineering resilience paradigm for conservation management, in the landscape context studied. The relevance of the ecological resilience paradigm in these ecosystems is obscured by limited data. We characterise forest fragment dynamics in terms of changes in indigenous species occupancy and functional dominance, and present a conceptual model for the management of forest fragment ecosystems

Space Structures: Issues in Dynamics and Control

A selective technical overview is presented on the vibration and control of large space structures, the analysis, design, and construction of which will require major technical contributions from the civil/structural, mechanical, and extended engineering communities. The immediacy of the U.S. space station makes the particular emphasis placed on large space structures and their control appropriate. The space station is but one part of the space program, and includes the lunar base, which the space station is to service. This paper attempts to summarize some of the key technical issues and hence provide a starting point for further involvement. The first half of this paper provides an introduction and overview of large space structures and their dynamics; the latter half discusses structural control, including control‐system design and nonlinearities. A crucial aspect of the large space structures problem is that dynamics and control must be considered simultaneously; the problems cannot be addressed individually and coupled as an afterthought

Online identification and nonlinear control of the electrically stimulated quadriceps muscle

A new approach for estimating nonlinear models of the electrically stimulated quadriceps muscle group under nonisometric conditions is investigated. The model can be used for designing controlled neuro-prostheses. In order to identify the muscle dynamics (stimulation pulsewidth-active knee moment relation) from discrete-time angle measurements only, a hybrid model structure is postulated for the shank-quadriceps dynamics. The model consists of a relatively well known time-invariant passive component and an uncertain time-variant active component. Rigid body dynamics, described by the Equation of Motion (EoM), and passive joint properties form the time-invariant part. The actuator, i.e. the electrically stimulated muscle group, represents the uncertain time-varying section. A recursive algorithm is outlined for identifying online the stimulated quadriceps muscle group. The algorithm requires EoM and passive joint characteristics to be known a priori. The muscle dynamics represent the product of a continuous-time nonlinear activation dynamics and a nonlinear static contraction function described by a Normalised Radial Basis Function (NRBF) network which has knee-joint angle and angular velocity as input arguments. An Extended Kalman Filter (EKF) approach is chosen to estimate muscle dynamics parameters and to obtain full state estimates of the shank-quadriceps dynamics simultaneously. The latter is important for implementing state feedback controllers. A nonlinear state feedback controller using the backstepping method is explicitly designed whereas the model was identified a priori using the developed identification procedure

New results in feedback control of unsupported standing in paraplegia

The aim of this study was to implement a new approach to feedback control of unsupported standing and to evaluate it in tests with an intact and a paraplegic subject. In our setup, all joints above the ankles are braced and stabilizing torque at the ankle is generated by electrical stimulation of the plantarflexor muscles. A previous study showed that short periods of unsupported standing with a paraplegic subject could be achieved. In order to improve consistency and reliability and to prolong the duration of standing, we have implemented several modifications to the control strategy. These include a simplified control structure and a different controller design method. While the reliability of standing is mainly limited by the muscle characteristics such as reduced strength and progressive fatigue, the results presented here show that the new strategy allows much longer periods (up to several minutes) of unsupported standing in paraplegia