Recent Technology Advancements in Smart City Management: A Review

The rapid population growth, insecure lifestyle, wastage of natural resources, indiscipline behavior of human beings, urgency in the medical field, security of patient information, agricultural-related problems, and automation requirements in industries are the reasons for invention of technologies. Smart cities aim to address these challenges through the integration of technology, data, and innovative practices. Building a smart city involves integrating advanced technologies and data-driven solutions to enhance urban living, improve resource efficiency, and create sustainable environments. This review presents five of the most critical technologies for smart and/or safe cities, addressing pertinent topics such as intelligent traffic management systems, information and communications technology, blockchain technology, re-identification, and the Internet of Things. The challenges, observations, and remarks of each technology in solving problems are discussed, and the dependency effects on the technologies’ performance are also explored. Especially deep learning models for various applications are analyzed. Different models performance, their dependency on dataset size, type, hyper-parameters, and the non-availability of labels or ground truth are discussed

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Mechanical behaviour of adhesively bonded composite single lap joints under quasi-static and impact conditions with variation of temperature and overlap

The use of adhesively bonded joints in structural components for the automotive industry has significantly increased over the last years, supported by the widespread integration of composite materials. This synergy allows vehicle manufacturers to offer a significant weight reduction of the vehicle allowing for fuel and emissions reduction and, at the same time, providing high mechanical strength. However, to ensure vehicle safety, the crashworthiness of these adhesive joints must be assessed, to evaluate if the structures can sustain large impact loads, transmitting the load and absorbing the energy, without damaging the joint. The novelty of this work is the study of the strain rate dependent behaviour of unidirectional composite adhesive joints bonded with a ductile epoxy crash resistant adhesive, subjected to low and high testing temperatures and using different overlap lengths. It was demonstrated that joints manufactured with this type of adhesive and composite substrates can exhibit excellent quasi-static and impact performance for the full range of temperatures tested. Increasing the overlap length, and independently of the testing temperature, it was observed an increase of energy absorbed for both quasi-static and impact loads, this is of considerable importance for the automotive industry, demonstrating that composite joints exhibit higher performance under impact. </jats:p

Mode I fracture toughness of CFRP as a function of temperature and strain rate

Composite structures currently used in the automotive industry must meet strict requirements for safety reasons. They need to maintain strength under varied temperatures and strain rates, including impact. It is therefore critical to fully understand the impact behaviour of composites. This work presents experimental results regarding the influence of a range of temperature and strain rates on the fracture energy in mode I, GIC, of carbon fibre reinforced plastic plates. To determine GIC as a function of temperature and strain rate, double cantilever beam specimens were tested at 20, 80 and −30℃, with strain rates of 0.2 and 11 s−1. A complementary numerical study was performed with the aim of predicting strength using the measured values. This work has demonstrated a significant influence of the strain rate and temperature on GIC of the composite materials, with higher strain rates and lower temperatures causing a decrease in the GIC values. </jats:p

Experimental and numerical study of the dynamic response of an adhesively bonded automotive structure

Based on economic and environmental factors related to energy efficiency, the automotive industry is being increasingly encouraged to design lighter structures, making use of adhesive bonding in vehicle body frames. To meet the standards of the automotive sector, adhesive joints must provide high strength and stiffness, low cost and good energy absorption at a component level, thereby ensuring good impact strength and passenger safety. This work aims to study, at room temperature (24°C), the impact response of a real scale automotive structure bonded with a crash-resistant epoxy, allowing to access the suitability of adhesives for automotive structural purposes. The epoxy adhesive was found to successfully transfer the loads to the aluminium substrates and not to compromise the integrity of the structure, as its failure was dominated by the behaviour of aluminium. Results obtained with a numerical model of the component were found to be in close agreement with the experimental failure load, demonstrating that numerical analysis can be a viable tool to predict the structure’s behaviour. In addition, a polyurethane was used as an alternative to the epoxy system to bond the structure, proving that the joint behaves better in the presence of a more flexible adhesive, as no failure was found for this case. Aluminium single-lap joints with two adhesive thicknesses were tested as a complement to understand the influence of this parameter on the impact response of a joint, showing a 21% decrease in strength when the highest thickness was used. </jats:p

Displacement rate effect in the fracture toughness of glass fiber reinforced polyurethane

Composite structures currently used in the oil industry must meet strict requirements for design and safety reasons. They need to maintain strength under varied displacement rates throughout its lifetime. It is therefore critical to fully understand the fracture behavior of such composites. This work presents experimental results regarding the influence of a range of displacement rates on the fracture energy in mode I, GIc, of glass fiber reinforced polyurethane used in the oil industry to repair and reinforce pipelines with corrosion damage. To determine GIc as a function of displacement rate, double cantilever beam specimens were tested, with displacement rates of 2, 20 and 200 mm/min with different thicknesses. A complementary numerical study was performed with the aim of predicting strength using the measured values. This work has demonstrated a significant influence of the strain rate and composite thickness on GIC of the composite materials, with higher rates and thicker specimens causing an increase in the GIC values. </jats:p

Numerical study of mode I fracture toughness of carbon-fibre-reinforced plastic under an impact load

The main objective of this work is, by using cohesive zone modelling, to compute the fracture toughness behaviour in mode I of unidirectional carbon-fibre-reinforced plastic subjected to an impact load at 4.7 m/s. To perform this task, double-cantilever beam specimens were simulated, with its opening displacement and crack propagation being assessed, as well as the evolution of strain rate through the test. Therefore, by plotting the crack propagation, it was possible to calculate the fracture toughness in mode I ( GIC). A comparison of the numerical results with experimental tests previously performed by using a drop weight falling-wedge impact test equipment was made, allowing to infer that the numerical approach, based on a triangular cohesive zone modelling, is capable to predict the behaviour of such specimens under impact, accurately obtain GIC, and to determine the value of strain rate achieved through the test. </jats:p

Road networks structure analysis: A preliminary network science-based approach

Road network studies attracted unprecedented and overwhelming interest in recent years due to the clear relationship between human existence and city evolution. Current studies cover many aspects of a road network, for example, road feature extraction from video/image data, road map generalisation, traffic simulation, optimisation of optimal route finding problems, and traffic state prediction. However, analysing road networks as a complex graph is a field to explore. This study presents comparative studies on the Porto, in Portugal, road network sections, mainly of Matosinhos, Paranhos, and Maia municipalities, regarding degree distributions, clustering coefficients, centrality measures, connected components, k-nearest neighbours, and shortest paths. Further insights into the networks took into account the community structures, page rank, and small-world analysis. The results show that the information exchange efficiency of Matosinhos is 0.8, which is 10 and 12.8% more significant than that of the Maia and Paranhos networks, respectively. Other findings stated are: (1) the studied road networks are very accessible and densely linked; (2) they are small-world in nature, with an average length of the shortest pathways between any two roads of 29.17 units, which as found in the scenario of the Maia road network; and (3) the most critical intersections of the studied network are 'Avenida da Boavista, 4100-119 Porto (latitude: 41.157944, longitude: - 8.629105)', and 'Autoestrada do Norte, Porto (latitude: 41.1687869, longitude: - 8.6400656)', based on the analysis of centrality measures