Framework for engineering design systems architectures evaluation and selection: case study

Engineering companies face the challenge of developing complex Engineering Design Systems. These systems involve huge financial, people, and time investments within an environment that is characterised by continuously changing technologies and processes. Systems architecture provides the strategies and modelling approaches to ensure that adequate resources are spent in developing the possible To Be states for a target system. Architecture selection and evaluation involves evaluating different architectural alternatives with respect to multiple criteria, hence an Architecture Evaluation Framework which evaluates and down selects the appropriate architectures solutions is crucial to assess how these systems will deliver value over their lifetime, and where to channel the financial and human investments to maximize benefit delivered to the business’ bottom line. In this paper, an evaluation and selection architecture framework is proposed, which targets to maximise the alignment of Engineering Design Systems with business goals based on a quality centric architecture evaluation approach. The framework utilised software Quality Attributes as well as SWOT (Strength, Weakness, Opportunity, Threat) and PEST (Political, Economic, Social, Technological) analyses to capture different viewpoints related to technical, political and business context. The framework proposed employing AHP (Analytical Hierarchy Process) to quantitatively elicit relationships between Quality Attributes trade-offs and architectural characteristics. The framework was applied to a real case study considering five Engineering Design Systems alternative architectures, where workshops with subject matter experts and stakeholders were held to reach an informative decision, that maximise architectural quality, whilst maintaining business alignment

FE Modeling of CFRP-Retrofitted RC Frames with Masonry Infill Walls

A number of numerical and experimental studies have been reported in recent literature to investigate the effects of infill walls on the seismic response of RC infilled frames. Many experimental studies used CFRP sheets as an external bracing system for retrofitting the infilled RC frames. It has been found that the common mode of failure of such retrofitted frames is the debonding of the CFRP-concrete adhesive material. In the current study, the behaviour of CFRP retrofitted infilled RC frames was investigated with a finite element micro model. In that model, a four-node shell element was used for modeling the concrete, infill panel and CFRP sheets. The interaction between concrete frame and infill panel was modelled using contact surfaces to allow the occurrence of separation and prevent penetration. Nonlinearities of the concrete, infill panel, steel and CFRP sheets were considered. To allow the occurrence of debonding mode of failure, the adhesive layer was modelled using cohesive surface-to-surface interaction model, which assumes that the failure of cohesive bond is characterized by progressive degradation of the cohesive stiffness, which is driven by a damage process based on the fracture energy. The proposed model was verified using experimental results from the literature. Results indicated that the cohesive model could capture the debonding mode of failure which has been observed experimentally. The validated micro model was used to investigate the effects of the strip end area, the anchor location and partial bonding of the CFRP sheet to the infill panel surface on the behaviour of infilled frames. The results of parametric study showed that, to get the highest efficiency of the CFRP retrofitted infilled frame, bonding about 25% only of the diagonal length from each end is sufficient to get the same behaviour of the totally bonded sheet

Laparoscopic ovarian drilling-plus: a one-stop management approach for PCO-associated infertility

Background: The current study aims to estimate additional values of laparoscopic intervention for diagnosis and treatment of concomitant pelvic pathologies among infertile women with clomiphene-resistant polycystic ovarian syndrome (PCOS) subjected to laparoscopic ovarian drilling (LOD) in comparison to non-PCOS infertile women subjected to diagnostic/therapeutic laparoscopy.Methods: A prospective cross sectional observational study was carried out in the Endoscopic unit of a tertiary care university hospital.  The study included 232 infertile women planned for laparoscopy were divided into a study group A (116 cases) with clomiphene-resistant PCOS and a control group B (116 cases) without PCOS. Each group was further subdivided into two subgroups according to the presence and absence of risk factors (RF) for adhesion formation. Diagnostic/operative laparoscopy was done. The main study outcome was the prevalence of any pelvic abnormalities seen during laparoscopy.Results: Both groups showed insignificant difference regarding socio-demographic history and basic data. Laparoscopy detected pelvic pathologies in 44 cases (37.9%) and 86 cases (74.1%) in both groups respectively. In group A, we diagnosed pelvic pathologies in 29 (32.6%) and 15 (55.6%) cases with and without RF respectively while in group B they were diagnosed in 76 (84.4%) and 10 (38.5%) cases with and without RF respectively. If compared to women with unexplained infertility, PCO patients without risk factors have an insignificant but higher prevalence of pelvic abnormalities. All concomitant pelvic pathologies in both groups were treated on a one-stop (see and treat) basis.Conclusions: Detection and proper management of associated pelvic pathologies at laparoscopy is a valuable additional advantage of LOD particularly in women with positive risk factors. LOD plus see and treat associated pathologies is a time saving and prompt management approach for women with PCO–associated infertility

Effect of Electric Fields on Silicon-Based Monolayers

Electric fields can induce bond breaking and bond forming, catalyze chemical reactions on surfaces, and change the structure of self-assembled monolayers on electrode surfaces. Here, we study the effect of electric fields supplied either by an electrochemical potential or by conducting atomic force microscopy (C-AFM) on Si-based monolayers. We report that typical monolayers on silicon undergo partial desorption followed by the oxidation of the underneath silicon at +1.5 V vs Ag/AgCl. The monolayer loses 28% of its surface coverage and 55% of its electron transfer rate constant (ket) when +1.5 V electrochemical potential is applied on the Si surface for 10 min. Similarly, a bias voltage of +5 V applied by C-AFM induces complete desorption of the monolayer at specific sites accompanied by an average oxide growth of 2.6 nm when the duration of the bias applied is 8 min. Current-voltage plots progressively change from rectifying, typical of metal-semiconductor junctions, to insulating as the oxide grows. These results define the stability of Si-based organic monolayers toward electric fields and have implication in the design of silicon-based monolayers, molecular electronics devices, and on the interpretation of charge-transfer kinetics across them

Nanoscale Silicon Oxide Reduces Electron Transfer Kinetics of Surface-Bound Ferrocene Monolayers on Silicon

Functionalizing Si with self-assembled monolayers (SAMs) paves the way for integrating the semiconducting properties of Si with the diverse properties of organic molecules. Highly packed SAMs such as those formed from alkyl chains protect Si from reoxidation in an ambient environment. Such monolayers have been largely considered oxide-free, but the effect of nanoscale reoxidation on the electrochemical kinetics of Si-based SAMs remains unknown. Here, we systematically study the effect of the oxide growth on the electrochemical charge-transfer kinetics of ferrocene-terminated SAMs on Si by exposing the surfaces to ambient conditions for controlled periods of time. X-ray photoelectron spectroscopy and atomic force microscopy revealed a gradual growth of silicon oxide (SiOx) on the surfaces over time. The oxide growth is accompanied by a decrease in the ferrocene surface coverage and a concomitant decrease in the electron transfer rate constant (ket) measured by electrochemical impedance spectroscopy. The drop in ket is attributed to a greater spacing between the ferrocene moieties induced by the surface oxide, which in turn blocks lateral electron transfer between neighboring ferrocene moieties. These findings explain the highly scattered literature data on electron transfer kinetics for monolayers on Si and have implications for the proper design of Si-based molecular electronic devices

Spontaneous S–Si bonding of alkanethiols to Si(111)–H: towards Si–molecule–Si circuits

We report the synthesis of covalently linked self-assembled monolayers (SAMs) on silicon surfaces, using mild conditions, in a way that is compatible with silicon-electronics fabrication technologies. In molecular electronics, SAMs of functional molecules tethered to gold via sulfur linkages dominate, but these devices are not robust in design and not amenable to scalable manufacture. Whereas covalent bonding to silicon has long been recognized as an attractive alternative, only formation processes involving high temperature and/or pressure, strong chemicals, or irradiation are known. To make molecular devices on silicon under mild conditions with properties reminiscent of Au–S ones, we exploit the susceptibility of thiols to oxidation by dissolved O2, initiating free-radical polymerization mechanisms without causing oxidative damage to the surface. Without thiols present, dissolved O2 would normally oxidize the silicon and hence reaction conditions such as these have been strenuously avoided in the past. The surface coverage on Si(111)–H is measured to be very high, 75% of a full monolayer, with density-functional theory calculations used to profile spontaneous reaction mechanisms. The impact of the Si–S chemistry in single-molecule electronics is demonstrated using STM-junction approaches by forming Si–hexanedithiol–Si junctions. Si–S contacts result in single-molecule wires that are mechanically stable, with an average lifetime at room temperature of 2.7 s, which is five folds higher than that reported for conventional molecular junctions formed between gold electrodes. The enhanced “ON” lifetime of this single-molecule circuit enables previously inaccessible electrical measurements on single molecules

Reduced graphene oxide-silicon interface involving direct Si-O bonding as a conductive and mechanical stable ohmic contact

Metal-semiconductor junctions are essential contacts for semiconductor devices, but high contact junction resistance is a limiting operational factor. Here, we establish an ohmic contact of low resistance of <4 × 10−6Ω cm2between platinum and n-type Si (111)-H surfaces. This involved Si-O covalent bonding a monolayer of graphene oxide (GO) to the Si surface followed by electrochemical reduction to form reduced graphene oxide (rGO). Current-voltage plots demonstrate that the GO/rGO transformation is associated with a change from a rectifying to an ohmic contact. The process is a viable method for constructing semiconductor-rGO interfaces and demonstrates that GO/rGO monolayers can be used as active components in tuning the contact resistance of metal-semiconductor junctions

Drought Susceptibility Index; a Preferred Criterion in Screening for Tolerance in Soybean

Soybean (Glycine max L.) yield and yield related traits are constrained by drought. Adaptation of soybean to changing environment could be improved by exploitation and introgression of diverse germplasm in breeding program. In present study, the response to drought conditions, especially at flowering stage, was evaluated to determine the potential soybean germplasm for future soybean breeding programs in Pakistan. Field experiment was conducted under two water regimes i.e. well-water and water-limited, to assess the effect of drought in seed yield and yield related traits. Although, drought led to overall reduction of ~15 % in thousand seed weight but still some soybean genotypes performed relatively better under water-limited conditions. These genotypes were also tolerant to drought, with a drought susceptibility index of \u3c 0.5. PCA also explained the pattern of variation existing in soybean germplasm grown under given water regimes i.e. well-water and water-limited conditions. The identified soybean genotypes could be a favorable resource to introduce high yielding soybean in local environment

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was USD 92 492 million using approach 1 and USD 73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was USD 95 004 million using approach 1 and USD 75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially.publishedVersio