An Inverse Problem Method for Overall Heat Transfer Coefficient Estimation in a Partially Filled Rotating Cylinder

The objective of this article is to study the estimation of an overall heat transfer coefficient in a partially filled rotating cylinder. Herein is an inverse analysis for estimating the overall heat transfer coefficient in an arbitrary cross-section of the aforementioned system from the temperatures measured on the shell. The material employs the finite-volume method to solve the direct problem. The hybrid effective algorithm applied here contains the local optimization algorithm to estimate the unknown parameter by minimizing the objective function. The data measured here are simulated by adding random errors to the exact solution. An investigation is made of the impact of the measurement errors on the accuracy of the inverse analysis. Two-optimization algorithms in determining the overall heat transfer coefficient are used. It is determined that the Conjugate Gradient Method is better than the Levenberg-Marquardt Method because the former produces greater accuracy for the same measurement errors. The resulting observation indicates that good agreement exists between the exact value and estimated result for both algorithms.     

Numerical Investigation of the Inlet Baffle,Header Geometry,and Triangular Fins Effects on Plate-Fin Heat Exchangers Performance

In this study, the optimal location of baffle in the header of air-to-air plate heat exchangers and the geometry of the header and the effects of triangular fins arrays on the effectiveness were numerically investigated for different flow rates and Reynolds numbers on different models. The main purpose of inlet baffle and geometry changes is to improve the pattern of flow distribution and assist flow uniformity. The investigations show that the optimal location of the inlet baffle with high Reynolds numbers has an insignificant effect on effectiveness, while with Reynolds numbers 250–3000, the effectiveness is affected significantly by baffle location. On the other hand, the reduction in flow gradients by changes in geometry can improve flow distribution. Moreover, investigations show that the increase in fin density (fins/mm) up to a specific value can enhance the effectiveness. In the present study, the Colburn j-factor behavior versus different Reynolds numbers, velocity distributions, pressure drops, and velocity vectors is examined.     

“Time-to-failure” prediction for a polymer-polymer swivelling joint

The growing competition in the market demands a better performance from any product in terms of availability, reliability, maintainability and failure free life. However there a number of engineering as well as environmental factor that influence the performance of a product. Wear is one of the critical factors, which influences the reliability and useful life of mechanical components. Therefore, the ability to predict wear at the development stage enables the designers to come up with a better design, longer useful life and more reliable products. Moreover, the prediction of time-to-failure for a component will lead to better maintenance helping to avoid catastrophic effects of unexpected failures. This paper presents a methodical approach for predicting sliding wear and hence the remaining useful life for a polymer-polymer sliding joint. The major stages of the approach are: tribo-system examination, experimentation, experimental wear coefficient determination and model formation.     

Tracking the sources of salmonella in ground beef produced from nonfed cattle

The objective of this study was to determine the source(s) of Salmonella contamination in ground beef. One hundred dairy cows were harvested in a U.S. commercial beef processing plant. Samples of hides, carcasses after hide removal and before exposure to antimicrobial intervention, carcasses after all antimicrobial interventions, superficial cervical lymph nodes from the chuck, trim, ground beef, and air were obtained. Ninety-six percent of the hide samples, 47% of the carcasses before intervention, 18% of the lymph nodes, 7.14% of the trim, and 1.67% of the ground beef samples were positive for Salmonella. None of the samples obtained from the carcasses after the full complement of interventions and none of the air samples were positive for Salmonella. All Salmonella-positive samples were subjected to pulsed-field gel electrophoresis, and eight DNA Xba I restriction patterns were identified. The majority of isolates had one of two restriction digest patterns. The strain isolated from ground beef had the same pattern as the strains isolated from hides and from carcasses immediately after hide removal. The Salmonella isolates from trim samples and lymph nodes also had the same restriction digest pattern. These results indicate that hide and lymph nodes are the most likely sources of Salmonella in ground beef. Dressing practices that effectively reduce or eliminate the transfer of bacteria from hide to carcass and elimination of lymph nodes as a component of raw ground beef should be considered as measures to reduce Salmonella contamination of ground beef. Because total elimination of lymph nodes from ground beef is not possible, other approaches should be explored. Easily accessible lymph nodes could be screened for Salmonella very early in the slaughter process. When the results are positive for Salmonella, the corresponding carcasses should be fabricated separately at the end of the production run, and the trim from these carcasses should be subjected to a treatment that destroys Salmonella.     

Controlling floodwater mosquitoes by river regulation

Floodwater mosquitoes cause serious problems especially the spread of mosquito‐borne diseases. The main challenge is to implement acceptable general mitigation methods. In recent years, encouraging steps have been taken in favour of developing more sustainable measures such as modern biological methods. The novelty of the present study is in suggesting an alternative green method that can eliminate the use of any secondary biological or chemical agents. The method is based on establishing an alternative river regulation scheme that limits flooding of high‐risk lowland areas. A combined hydrodynamic modelling and optimization method gave effective river regulation schemes. The main idea is to maintain the total power production for a modified inflow hydrograph. The approach was applied to a 30‐km reach of the Österdalälven River located in central Sweden. It was found that with the specific constraints of the site a reduction of about 8% of lowland flood areas is possible if the inflow hydrograph is moderately modified by 20%. Higher reductions are possible by further modification of the hydrograph. The proposed method has a general character controlled by the specific site requirements of a critical flow or a water surface elevation. Based on the foregoing information, the method can be applied to similar sites.     

Evaluating the safety impacts of the number and arrangement of lanes on freeway exit ramps

The primary objective of this study is to evaluate the impacts of the number and arrangement of lanes on freeway exit ramps on the safety performance of freeway diverge areas. The research team collected crash data at 343 freeway segments in the state of Florida. Four different types of exit ramps were considered in this study. They were defined as type 1, type 2, type 3, and type 4 exit ramps respectively. Cross-sectional comparison was conducted for comparing crash frequency, crash rate and crash severity between different types of freeway exit ramps. Crash prediction models were developed to identify the factors that contribute to the crashes reported at selected freeway segments and to provide quantified information regarding the safety impacts of different freeway exit ramps. It was found that the ramp and freeway AADT, posted speed limit on freeway, deceleration lane length, right shoulder width, and the type of exit ramp significantly affected the safety performance of freeway diverge areas. The study demonstrated the safety benefits of using lane-balanced exit ramps. Based on the crash prediction models, replacing a type 1 exit ramp (lane-balanced) with a type 2 exit ramp (not lane-balanced) will increase crash counts at freeway diverge areas by 68.33%. Replacing a type 3 ramp (lane-balanced) with a type 4 ramp (not lane-balanced) will increase crash counts at freeway diverge areas by 32.20%.     

The comparison of incomplete sensitivities and Genetic algorithms applications in 3D radial turbomachinery blade optimization

In the present work, a centrifugal pump impeller’s blades shape was redesigned to reach a higher efficiency in turbine mode using two different optimization algorithms: one is a local method as incomplete sensitivities–gradient based optimization algorithm coupled by 3D Navier–Stokes flow solver, and another is a global method as Genetic algorithms and artificial neural network coupled by 3D Navier–Stokes flow solver. New impeller was manufactured and tested in the test rig. Comparison of the local optimization method results with the global optimization method results showed that the gradient based method has detected the global optimum point. Experimental results confirmed the numerical efficiency improvement in all measured points. This study illustrated that the developed gradient based optimization method is efficient for 3D radial turbomachinery blade optimization.     

Influence of seismic incident angle on response uncertainty and structural performance of tall asymmetric structure

The estimation of critical seismic response of a structure is complicated in nature due to the uncertain distribution of the internal forces under multidirectional seismic excitations. One of the important concerns inherent to this complication is the uncertainty associated with the final design direction as different seismic directions result in different seismic responses. In this regard, this research provides a detailed examination of (1) response‐to‐response and record‐to‐record variability under varying seismic orientations, (2) quantification of seismic response uncertainties and (3) the seismic performance of asymmetric structure in the context of conservative/nonconservative seismic design. With the mentioned research objectives, a realistic case study asymmetric structure under the influence of varying bidirectional seismic excitations was evaluated. It has been argued in this research that the seismic excitations applied at structure's reference axes are very unlikely to demonstrate maximum response for all response quantities simultaneously, even if it results in a peak response for a particular seismic response quantity. This research is particularly helpful for the critical assessment of directionality influence on asymmetric structures prior to making any decision during thestructural design process. Substantial arguments have been presented to emphasize the inclusion of the investigation of seismic response uncertainty in practical design of critical asymmetric structures.     

The effect of magnesium on bioactivity,rheology and biology behaviors of injectable bioactive glass-gelatin-3-glycidyloxypropyl trimethoxysilane nanocomposite-paste for small bone defects repair

Injectable bioactive glass-based pastes represent promising biomaterials to fill small bone defects thus improving and speed up the self-healing process. Accordingly, injectable nanocomposite pastes based on bioactive glass-gelatin-3-glycidyloxypropyl trimethoxysilane (GPTMS) were here synthesized via two different glasses 64SiO₂. 27CaO. 4MgO. 5P₂O₅ (mol.%) and 64SiO₂.31CaO. 5P₂O₅ (mol.%). In particular, the effects of MgO on bioactivity, rheology, injectability, disintegration resistance, compressive strength and cellular behaviors were investigated. The results showed that the disintegration resistance and compressive strength of the composite were improved by the replacement of MgO; thus, leading to an increase in the amount of storage modulus (G′) from 26800 to 43400 Pa, equal to an increase in the viscosity of the paste from 136 × 10³ to 219 × 10³ Pa s. Since the release rate of ions became more controllable, the formation of calcite was decreased after immersion of the Mg bearing samples in the SBF solution. Specimens’ cytocompatibility was firstly verified towards human osteoblasts by metabolic assay as well as visually confirmed by the fluorescent live/dead staining; finally, the ability of human fibroblasts to penetrate within the pores of 3D composites was verified by a migration assay simulating the devices repopulation upon injection in the injured site.     

Rheology,injectability, and bioactivity of bioactive glass containing chitosan/gelatin,nano pastes

Bioactive pastes containing bioactive sol–gel derived glass (BG) and various amounts of chitosan (Cn) and gelatin (Gel) were prepared in this study. To be exact, three pastes were prepared by mixing 25 parts by weight of glass powder with (a) 100 parts by weight of a 3 wt% acetic acid-based chitosan solution, (b) 100 parts by weight of a 3 wt% water-based gelatin solution, and (c) 100 parts by weight of a solution containing equal amounts of the above-mentioned solutions. The bioactivity of the composite samples was evaluated by the immersion of the prepared pastes into the simulated body fluid (SBF) solution. The samples were also analyzed by X-ray diffractometry (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM), Fourier transform infrared (FTIR), and atomic absorption spectroscopy (AAS). The results indicated better apatite formation capacity on the glass-/chitosan-/gelatin-injected paste after 14 days. Furthermore, unlike the chitosan containing paste, the gelatin-containing sample was injectable and displayed viscoelastic behavior as determined by conducting the rheology test in oscillation mode. In addition, while chitosan made the paste more viscous, it improved the washout resistance when compared to the gelatin-containing sample. The experimental results also indicate the formation of spherical calcites in the pastes prior to immersion into the SBF solution.