Building Failure Causes in Nigeria and Mitigating Roles by Engineering Regulation and Monitoring

This paper assessed some of the reported cases of building failures and their possible causes in Nigeria between 1977 and 2011. The reported major failure causes are structural failure (SF), Carelessness (CLSS), poor workmanship (PW), poor supervision (PS), poor materials (PM), and quackery (Q).These causes of failure were subjected to Chi-Square statistical test at 5% significant level and 4 degree of freedom to know the most common cause of failure in Nigeria. The analysis showed quackery as the principal culprit in the reported building failures in Nigeria with prevalence of 8 over poor supervision being the minimum in occurrence. Structural failure occurred 5 times, while poor materials, carelessness and poor workmanship occurred 4, 2 and 2 respectively. The Council for the Regulation of Engineering in Nigeria (COREN) with Engineering Regulation and Monitoring (ERM) as her arm as a technical professional group discouraging quackery and failures generally in Engineering Practice. The holistic approach needs effective training of Engineers starting with strong mathematical and scientific background at the secondary and tertiary education levels in conjunction with rigorous field and Industrial training exercises. There after effective scrutiny, professional registration process of competent engineers is followed.

Comparison of engineering failures and seismic responses of 500 kV transformer-bushing systems in the 2022 Luding earthquake

Cemented and mechanically clamped types of end fittings(fitting-C and fitting-M)are commonly used in transformer bushings.During the Luding Ms 6.8 earthquake that occurred in China on September 5,2022,all transformer bushings with the two types of end fittings in a 500 kV substation were damaged.Post-earthquake field investigations were conducted,and the failures of the two types of bushings were compared.Two elementary simulation models of the transformer-bushing systems were developed to simulate the engineering failures,and further compute their seismic responses for comparison.The results indicate that the hitch lugs of the connection flange are structurally harmful to seismic resistance.Fitting-M can decrease the bending stiffness of the bushing due to the flexible sealing rubber gasket.Since it provides a more flexible connection that dissipates energy,the peak accelerations and relative displacements at the top of the bushing are significantly lower than those of the bushing with fitting-C.Compared with fitting-C,fitting-M transfers the high-stress areas from the connection flange to the root of the porcelain,so the latter becomes the most vulnerable component.Fitting-M increases the failure risk of the low-strength porcelain,indicating the unsuitability of applying it in high-intensity fortification regions.

An Evaluation of Human Error Probabilities for Critical Failures in Auxiliary Systems of Marine Diesel Engines

Human error,an important factor,may lead to serious results in various operational fields.The human factor plays a critical role in the risks and hazards of the maritime industry.A ship can achieve safe navigation when all operations in the engine room are conducted vigilantly.This paper presents a systematic evaluation of 20 failures in auxiliary systems of marine diesel engines that may be caused by human error.The Cognitive Reliability Error Analysis Method(CREAM)is used to determine the potentiality of human errors in the failures implied thanks to the answers of experts.Using this method,the probabilities of human error on failures were evaluated and the critical ones were emphasized.The measures to be taken for these results will make significant contributions not only to the seafarers but also to the ship owners.

Post-Failure Rheological Properties of Rockmass ——An Important Object of Study for Engineering Rockmass Mechanics

Post failure rheology, as an important deformable behavior of average to very poor rockmass,is discussed in this paper. Three kinds of deformations, transition deformation, post failure rheological deformation and swelling deformation, are also introduced for they are totally different from that of traditional concepts. Transition and post failure deformations are sensitive to the environmental factors, and need to be studied in the future.

Corrosion engineering on AlCoCrFeNi high-entropy alloys toward highly efficient electrocatalysts for the oxygen evolution of alkaline seawater

Seawater splitting is a prospective approach to yield renewable and sustainable hydrogen energy.Complex preparation processes and poor repeatability are currently considered to be an insuperable impediment to the promotion of the large-scale production and application of electrocatalysts.Avoiding the use of intricate instruments,corrosion engineering is an intriguing strategy to reduce the cost and presents considerable potential for electrodes with catalytic performance.An anode comprising quinary AlCoCrFeNi layered double hydroxides uniformly decorated on an AlCoCrFeNi high-entropy alloy is proposed in this paper via a one-step corrosion engineering method,which directly serves as a remarkably active catalyst for boosting the oxygen evolution reaction(OER)in alkaline seawater.Notably,the best-performing catalyst exhibited oxygen evolution reaction activity with overpotential values of 272.3 and 332 mV to achieve the current densities of 10 and100 mA·cm^(-2),respectively.The failure mechanism of the obtained catalyst was identified for advancing the development of multicomponent catalysts.

Failure Assessment of Aero-engine Support Structure due to Blade-off

Aero-engine blade-off event could cause serious malfunction and endanger flight safety,which is an important issue widely concerned for a long period.This paper presents a comprehensive review on the regulation requirements,the major research methods and status at home and abroad.Firstly,the relevant certification regulations and standards about aero-engine structure safety due to blade-off event were overviewed and the research gaps between the abroad and the domestic were compared.Then,the simulation and experimental methodologies on aero-engine supporting structures undertake abnormal load due to blade-off event were discussed as major issue.Finally,the safety certification verification technology system for aero-engine support structures during blade-off event was proposed.

CAUSALITY DIAGRAM BASED SAFETY ANALYSIS OF MICRO TURBOJET ENGINE

An improved safety analysis based on the causality diagram for the complex system of micro aero-engines is presented.The study is examined by using the causality diagram in analytical failure cases due to rupture or pentration in the receiver of micro turbojet engine casing,and the comparisons are also made with the results from the traditional fault tree analysis.Experimental results show two main advantages：（1）Quantitative analysis which is more reliable for the failure analysis in jet engines can be produced by the causality diagram analysis;（2）Graphical representation of causality diagram is easier to apply in real test cases and more effective for the safety assessment.

RELIABILITY EVALUATION MODEL BASED ON DATA FUSION FOR AIRCRAFT ENGINES

Reliability evaluation for aircraft engines is difficult because of the scarcity of failure data. But aircraft engine data are available from a variety of sources. Data fusion has the function of maximizing the amount of valu- able information extracted from disparate data sources to obtain the comprehensive reliability knowledge. Consid- ering the degradation failure and the catastrophic failure simultaneously, which are competing risks and can affect the reliability, a reliability evaluation model based on data fusion for aircraft engines is developed, Above the characteristics of the proposed model, reliability evaluation is more feasible than that by only utilizing failure data alone, and is also more accurate than that by only considering single failure mode. Example shows the effective- ness of the proposed model.

Advances in statistical mechanics of rock masses and its engineering applications

To efficiently link the continuum mechanics for rocks with the structural statistics of rock masses,a theoretical and methodological system called the statistical mechanics of rock masses(SMRM)was developed in the past three decades.In SMRM,equivalent continuum models of stressestrain relationship,strength and failure probability for jointed rock masses were established,which were based on the geometric probability models characterising the rock mass structure.This follows the statistical physics,the continuum mechanics,the fracture mechanics and the weakest link hypothesis.A general constitutive model and complete stressestrain models under compressive and shear conditions were also developed as the derivatives of the SMRM theory.An SMRM calculation system was then developed to provide fast and precise solutions for parameter estimations of rock masses,such as full-direction rock quality designation(RQD),elastic modulus,Coulomb compressive strength,rock mass quality rating,and Poisson’s ratio and shear strength.The constitutive equations involved in SMRM were integrated into a FLAC3D based numerical module to apply for engineering rock masses.It is also capable of analysing the complete deformation of rock masses and active reinforcement of engineering rock masses.Examples of engineering applications of SMRM were presented,including a rock mass at QBT hydropower station in northwestern China,a dam slope of Zongo II hydropower station in D.R.Congo,an open-pit mine in Dexing,China,an underground powerhouse of Jinping I hydropower station in southwestern China,and a typical circular tunnel in Lanzhou-Chongqing railway,China.These applications verified the reliability of the SMRM and demonstrated its applicability to broad engineering issues associated with jointed rock masses.

Rock engineering design of post-tensioned anchors for dams - A review

High-capacity, post-tensioned anchors have found wide-spread use, originally in initial dam design and construction, and more recently in the strengthening and rehabilitation of concrete dams to meet modern design and safety standards. Despite the advances that have been made in rock mechanics and rock engineering during the last 80 years in which post-tensioned anchors have been used in dam en- gineering, some aspects of the rock engineering design of high-capacity rock anchors for dams have changed relatively little over the last 30 or 40 years. This applies, in particular, to the calculations usually carried out to establish the grouted embedment lengths required for deep, post-tensioned anchors. These calculations usually make simplified assumptions about the distribution and values of rock-grout interface shear strengths, the shape of the volume of rock likely to be involved in uplift failure under the influence of a system of post-tensioned anchors, and the mechanism of that failure. The resulting designs are generally conservative. It is concluded that these aspects of the rock engineering design of large, post- tensioned rock anchors for dams can be significantly improved by making greater use of modern, comprehensive, numerical analyses in conjunction with three-dimensional （3D） models of the rock mass structure, realistic rock and rock mass properties, and the results of prototype anchor tests in the rock mass concerned.

A DEMATEL Approach Based on Fuzzy Sets for Evaluating Critical Factors of Gas Turbine in Marine Engineering

In power production,gas turbines are commonly used components that generate high amount of energy depending on size and weight.They function as integral parts of helicopters,aircrafts,trains,ships,electrical generators,and tanks.Notably,many researchers are focusing on the design,operation,and maintenance of gas turbines.The focal point of this paper is a DEMATEL approach based on fuzzy sets,with the attempt to use these fuzzy sets explicitly.Using this approach,the cause–effect diagram of gas turbine failures expressed in the literature is generated and aimed to create a perspective for operators.The results of the study show that,"connecting shaft has been broken between turbine and gear box"selected the most important cause factor and"sufficient pressure fuel does not come for fuel pump"is selected the most important effect factor,according to the experts.

Technology Research on Aviation Piston Engine Camshaft Repair

Based on the analysis of the piston engine camshatt common failure mode, combining the mechanical analysis and risk management means, the feasibility of its repair was much discussed, the repair technique are studied, and proved its correctness and effectiveness.

Thermo-Mechanical Analysis of a Typical Vehicle Engine Using PTC-Creo

In this work,a typical vehicle engine is modeled within PTC-Creo soft­ware,and its thermal,mechanical,and thermo-mechanical performance are evaluated.This is followed by the vibrational,fatigue,and buckling analy­sis of the assembly of components,which are the predominant failure caus­es.The results show that the least temperature gradient occurs in the center of the pin,which connects the piston to the connecting rod,the maximum displacement is seen just below the piston head,and the thermo-mechanical failure is caused mostly(about 85%)by the mechanical load rather than the thermal one.Also,in fatigue analysis,the minimum and maximum values for the safety factor are 0.63 and 5,respectively.The results can prevent the reoccurrence of similar failures and help the enhancement of the compo­nents’design and manufacturing process.

Earthquake Resistant Engineering and Application of Seismic Zonation Map of ChinaTechnicalInnovations

China is a country with high seismicity. It is very important for industry and structure to fortify against earthquakes. In this paper the outline of seismicity in China, the criteria for fortification against earthquakes and the contents of seismic zonation map of China are described. The contents of seismic safety evaluation for major construction projects, such as large dams, large bridges, long distance pipe lines for transporting oil and natural gas, nuclear plants, petrochemical enterprises and so on, are presented. Some geological disasters caused by destructive earthquake, such as earthquake caused collapse and landslide, liquefaction of saturated soil and earthquake fault and so on, are also presented. Preventive countermeasures for these disasters are discussed.

Analysis of Potential Causes of Safety Failure of New Energy Vehicle Power Batteries

The aim of this paper is to analyze the potential reasons for the safety failure of batteries for new-energy vehicles.Firstly,the importance and popularization of new energy batteries are introduced,and the importance of safety failure issues is drawn out.Then,the composition and working principle of the battery is explained in detail,which provides the basis for the subsequent analysis.Then,the potential impacts of factors such as overcharge and over-discharge,high and low temperature environments,internal faults,and external shocks and vibrations on the safety of the batteries are analyzed.Finally,some common safety measures and solutions are proposed to improve the safety of new energy batteries,in hopes of improving the safety of batteries for new-energy vehicle.

Augmented flight dynamics model for pilot workload evaluation in tilt-rotor aircraft optimal landing procedure after one engine failure

An augmented flight dynamics model is developed to extend the existing flight dynamics model of tilt-rotor aircraft for optimal landing procedure analysis in the event of one engine failure.Compared with the existing flight dynamics model, the augmented model involves with more pilot control information in cockpit and is validated against the flight test data. Based on the augmented flight dynamics model, the optimal landing procedure of XV-15 tilt-rotor aircraft after one engine failure is formulated into a Nonlinear Optimal Control Problem(NOCP), solved by collocation and numerical optimization method. The time histories of pilot controls in cockpit during the optimal landing procedure are obtained for the evaluation of pilot workload. An evaluation method which can synthetically quantify the pilot workload in time and frequency domains is proposed with metrics of aggressiveness and cutoff frequencies of pilot controls. The scale of the pilot workload is compared with those of the shipboard landing procedures, bob-up/bob-down and dash/quickstop maneuvers of UH-60 helicopter. The results show that the aggressiveness of pilot collective and longitudinal controls for the tilt-rotor aircraft optimal landing procedure after one engine failure are higher than those for UH-60 helicopter shipboard landing procedures up to the condition of sea state 4, while the pilot cutoff frequency of collective control is lower than that of the bob-up/bob-down maneuver but the pilot cutoff frequency of longitudinal control is higher than that of the dash/quick-stop maneuver. The evaluated pilot workload level is between Cooper–Harper HQR Level 2 and Level 3.

Study of helicopter autorotation landing following engine failure based on a six-degree-of-freedom rigid-body dynamic model

This paper focuses on the prediction of the safe autorotation landing operations of a helicopter following engine failure.The autorotation landing procedure is formulated as a nonlinear optimal control problem based on an augmented six-degree-of-freedom rigid-body flight dynamic model.First,the cost function and constraints are properly selected.The direct transcription approach is then employed to solve the optimal control problem.For a UH-60 helicopter,the optimal solutions with the rigid-body model are compared with those obtained using a two-dimensional point-mass model.It is found that the optimal solutions using the two different models show reasonably good agreement,and furthermore the optimal solutions using the rigid-body model involve the time histories of angular rates and attitudes,lateral velocity and position,as well as pitch controls.Finally the optimal control formulations with different cost functions are proposed for taking account of 1-s time delay and minimum touchdown speed.The calculated control strategies and trajectories are realistic.

Treatment of chronic heart failure in the 21st century: A new era of biomedical engineering has come

Chronic heart failure (CHF) is a challenging burden on public health. Therapeutic strategies for CHF have developed rapidly in the past decades from conventional medical therapy, which mainly includes administration of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, and aldosterone antagonists, to biomedical engineering methods, which include interventional engineering, such as percutaneous balloon mitral valvotomy, percutaneous coronary intervention, catheter ablation, biventricular pacing or cardiac resynchronization therapy (CRT) and CRT-defibrillator use, and implantable cardioverter defibrillator use;mechanical engineering, such as left ventricular assistant device use, internal artery balloon counteq^ulsation, cardiac support device use, and total artificial heart implantation;surgical engineering, such as coronary artery bypass graft, valve replacement or repair of rheumatic or congenital heart diseases, and heart transplantation (HT);regenerate engineering, which includes gene therapy, stem cell transplantation, and tissue engineering;and rehabilitating engineering, which includes exercise training, low-salt diet, nursing, psychological interventions, health education, and external counterpulsation/enhanced external counterpulsation in the outpatient department. These biomedical engineering therapies have greatly improved the symptoms of CHF and life expectancy. To date, pharmacotherapy, which is based on evidence-based medicine, large-scale, multi-center, randomized controlled clinical trials, is still a major treatment option for CHF;the current interventional and mechanical device engineering treatment for advanced CHF is not enough owing to its individual status. In place of HT or the use of a total artificial heart, stem cell technology and gene therapy in regenerate engineering for CHF are very promising. However, each therapy has its advantages and disadvantages, and it is currently possible to select better therapeutic strategies for patients with CHF according to cost-efficacy analyses of these therapies. Taken together, we think that a new era of biomedical engineering for CHF has begun.

Prediction of pilot workload in helicopter landing after one engine failure

This paper presents a method to predict the pilot workload in helicopter landing after one engine failure.The landing procedure is simulated numerically via applying nonlinear optimal control method in the form of performance index,path constraints and boundary conditions based on an augmented six-degree-of-freedom rigid-body flight dynamics model,solved by collocation and numerical optimization method.UH-60 A helicopter is taken as the sample for the demonstration of landing after one engine failure.The numerical simulation was conducted to find the trajectory of helicopter and the controls from pilot for landing after one engine failure with different performance index considering the factor of pilot workload.The reasonable performance index and corresponding landing trajectory and controls are obtained by making a comparison with those from the flight test data.Furthermore,the pilot workload is evaluated based on wavelet transform analysis of the pilot control activities.The workloads of pilot control activities for collective control,longitudinal and lateral cyclic controls and pedal control during the helicopter landing after one engine failure are examined and compared with those of flight test.The results show that when the performance index considers the factor of pilot workload properly,the characteristics of amplitudes and constituent frequencies of pilot control inputs in the optimal solution are consistent with those of the pilot control inputs in the flight test.Therefore,the proposed method provides a tool of predicting the pilot workload in helicopter landing after one engine failure.

Traffic Engineering for Proactive Failure Recovery of IP Networks

As a promising approach to improve network reliability, proactive failure recovery （PFR） re-routes failure affected traffic to backup paths without waiting for the completion of IP routing convergence. However the failure affected traffic may cause congestion if it is not carefully allocated over the backup paths according to their available capacity. A post failure traffic engineering （PostTE） scheme is proposed to balance the load in the PFR scheme. Loop-free backup paths are prepared in advance to cover all the potential single-link failures. The failure affected load is locally allocated to the backup paths through solving a linear programming （LP） problem. Most of the time, the maximum link utilization （MLU） of the network is minimized under both the failure and failure-free cases. For the tested education networks, the LP problem can be solved within milliseconds.