bluuebunny/crossref_metadata_2025 huggingface dataset:
Location choice determinants of Chinese and US firms in Africa: Does spatial interdependence play a role?
Authors: Lemi Adugna , Liu Liyan , Wright Ian A.
Published: March 2021

In an increasingly integrated global market, the nature and extent of spatial interdependence is one key factor influencing firms’ location decisions. Spatial interdependence often manifests itself in the form of agglomeration or congestion effects, not just within a country but also in a region. Using Chinese and US overseas investment data, this study presents empirical evidence on the role that neighbouring countries (third‐country effects) play in attracting Foreign Direct Investment (FDI) to a host country. The study's findings show that there is evidence of spatial interdependence both for Chinese and USA FDI flows to African countries. For both countries, the third country effects come through either explanatory variables (including market size, domestic credit, trade costs and the share of service sector), error term or the amount of FDI in neighbouring countries. The findings also show that there is more robust evidence that, unlike Chinese FDI, the US FDI takes into account the market potentials of not just a host country but also that of a neighbouring country in making investment location decisions.
Cataracts and phacoemulsification in the Siberian Husky: A retrospective and multicentric study (2008–2018)
Authors: Uhl Lisa K. , Henriksen Michala de Linde , Saxmose Nielsen Søren , Gemensky‐Metzler Anne J. , Sebbag Lionel , Todd Jeffrey M.
Published: March 2021

Purpose

To compare cataract characteristics and complications related to cataracts and phacoemulsification in the Siberian Husky (Huskies) versus other canine breeds (non‐Huskies).

Animals

A total of 50 Huskies (92 eyes) and 96 non‐Huskies (182 eyes) were evaluated.

Methods

Medical records of Huskies (at four university veterinary hospitals, 2008–2018) and non‐Huskies (Colorado State University, 2017–2018) diagnosed with cataracts were reviewed. Age of dog, cataract stage at presentation, and pre‐ and post‐operative complications were recorded and analyzed.

Results

Mean (±standard deviation) age at presentation was significantly lower in Huskies (3.5 ± 3.3 years) compared to non‐Huskies (9.5 ± 2.9 years) (p < .0001). Huskies more commonly presented with hereditary cataracts than non‐Huskies (84% versus 52%) and a significantly higher percentage of non‐Huskies presented with diabetic cataracts than Huskies (48% versus 16%;p = .0001). Cataract stage at presentation did not differ between Huskies and non‐Huskies. Phacoemulsification was performed in 40% (20 out of 50 dogs, 39 out of 92 eyes) of Huskies and 42% (40 out of 96 dogs, 74 out of 182 eyes) of non‐Huskies. Pre‐operative and post‐operative retinal detachment were more common in Huskies than non‐Huskies (13% versus 2% and 10% versus 1%, respectively) but the difference was not significant. Other post‐operative complications occurred with similar frequency in both groups (p ≥ .17).

Conclusions

Huskies evaluated for cataracts were younger and less likely to present with diabetic cataracts than other canine breeds and, although not statistically significant, had a clinically important increased risk of retinal detachment pre‐ and post‐phacoemulsification.
Understanding the role of therapeutic plasma exchange in COVID‐19: preliminary guidance and practices
Authors: Patidar Gopal K. , Land Kevin J. , Vrielink Hans , Rahimi‐Levene Naomi , Dann Eldad J. , Al‐Humaidan Hind , Spitalnik Steven L. , Dhiman Yashaswi , So ‐ Osman Cynthia , Hindawi Salwa I.
Published: March 2021

Background and objectives

Cytokine release syndrome in COVID‐19 is due to a pathological inflammatory response of raised cytokines. Removal of these cytokines by therapeutic plasma exchange (TPE) prior to end‐organ damage may improve clinical outcomes. This manuscript is intended to serve as a preliminary guidance document for application of TPE in patients with severe COVID‐19.

Material and methods

The available literature pertaining to the role of TPE for treatment of COVID‐19 patients was reviewed to guide optimal management. It included indication, contraindication, optimal timing of initiation and termination of TPE, vascular access and anticoagulants, numbers and mode of procedures, outcome measures and adverse events.

Results

Out of a total of 78 articles, only 65 were directly related to the topic. From these 65, only 32 were acceptable as primary source, while 33 were used as supporting references. TPE in critically ill COVID‐19 patients may be classified under ASFA category III grade 2B. The early initiation of TPE for 1–1·5 patient’s plasma volume with fresh frozen plasma, or 4–5% albumin or COVID‐19 convalescent plasma as replacement fluids before multiorgan failure, has better chances of recovery. The number of procedures can vary from three to nine depending on patient response.

Conclusion

TPE in COVID‐19 patients may help by removing toxic cytokines, viral particles and/or by correcting coagulopathy or restoring endothelial membrane. Severity score (SOFA & APACHE II) and cytokine levels (IL‐6, C‐reactive protein) can be used to execute TPE therapy and to monitor response in COVID‐19 patients.
PRELIMINARY ASSESSMENT OF THE EFFECTS OF BLAST DESIGN FACTORS ON FRAGMENTATION AT LAFARGE KANTHAN LIMESTONE QUARRY, CHEMOR, PERAK
Authors: Shehu Shaib Abdulazeez , Mohd Hashim Mohd Hazizan , Awang Kechik Nur Aliah Hazirah
Published: March 2021

The results of blasting affect every other downstream operation in quarrying and mining process. Factors influencing blast results can be classified as either controllable or non-controllable. If desired fragmentation is to be obtained, the controllable factors (blast geometry and explosive properties) must be sufficiently designed to match the non-controllable ones (geological factors and legislative constraints). This study investigates the influence of blast design parameters on rock fragmentation. Six different blast designs were studied and analyzed. Rock samples were obtained from each face to evaluate the uniaxial compressive strength (UCS). Images of muck pile were captured using suitable digital camera. The images were uploaded into the WipFrag software to analyze the fragmentation resulting from the blasting. The particle size distribution of each blast was obtained, and the mean fragment size correlated with the blast design parameters. The percentage cumulative passing for gyratory crusher with the feed size of 1500 mm ranges between 92.8 to 100%. The stiffness ratio, powder factor and uniaxial compressive strength have high correlation with mean fragment size. The stiffness ratio increases with mean fragment size with a correlation coefficient of 0.89. The mean fragment size becomes finer with increase in powder factor with a correlation coefficient of 0.76. Powder factor also has a high correlation with the uniaxial compressive strength of the rock. The higher the uniaxial compressive strength of rock, the higher the powder factor needed for a specified fragment size. In this study, spacing to burden ratio has a very weak correlation with the fragment size. All the studied blast events produced good fragmentation with a uniformity index varying from 2.097 to 2.525.
EXPERIMENTAL COMPRESSION TESTS OF COLD-FORMED STEEL (CFS) TO VERIFY ITS CODE-BASED STRENGTH
Authors: Lejano Bernardo , De Jesus James Matthew , Yu Arvin Patrick
Published: March 2021

Cold-Formed Steel (CFS) is a good construction material because of its high strength-to-weight ratio, that is, it exhibits efficient load carrying capabilities in combination with its lightweight characteristics. Although CFS is already being used in construction, information on structural performance of locally-produced CFS in the Philippines is scarce. To date, the authors have not found any experimental study done in the Philippines regarding the structural performance of locally-produced CFS. In this study, C-section and Z-section are being studied since these members exhibit buckling failures that may be difficult to predict due to complexity of their section geometry. The objective of this paper is to present the performance of these CFS sections when subjected to concentric axial compression both experimentally and computationally. For the experimental part, the CFS members were subjected to axial compression using a hydraulic jack. High-speed video cameras were used to capture the different failure modes. For the computational aspect, provisions found in the National Structural Code of the Philippines (NSCP) were used to calculate the compression strength of the members. A total of 80 C-section specimens with 5 different lengths and 5 different thicknesses were tested. It was found that the strength calculations using the NSCP provisions were not consistent with the results of the compression tests. For shorter lengths, distortional buckling prevailed as the main failure, while for longer lengths, torsional-flexural buckling occurred. All of the predicted strengths were highly conservative. For the Z-section, a total of 180 specimens with 6 different lengths and 6 different thicknesses were tested. Torsional-flexural buckling was observed in majority of the specimens. Although most of the failure modes were predicted correctly, it was found that the predicted strengths using the NSCP were relatively high compared to the experimental results, thus non-conservative. Finite Element Method (FEM) analyses using ANSYS were conducted. Findings indicate that the experiment results agreed well with the FEM results.
BEHAVIOR OF PARTIAL STRENGTH OF BEAM-TO-COLUMN CONNECTION WITH GUSSET PLATE FOR COLD-FORMED STEEL SECTIONS
Authors: Firdaus Muhammad , Saggaff Anis , Md Tahir Mahmood , Aminuddin Kiagus Muhammad , Poi Ngian Shek , Siang Tan Cher , Ali Salih Musab Nimir , Mohammadhosseini Hossein , Sulaiman Arizu
Published: March 2021

The use of cold-formed steel (CFS) as part of a major construction has been rapidly increasing recently, as it is considered viable as an alternative to the conventional hot-rolled steel section. However, information about CFS as part of a non-composite system is still limited as the connection is designed as a pinned connection, only good for roof trusses and wall paneling. The aim of this research is to propose a connection for CFS sections that could enhance the strength of typical CFS connections, from pinned to partial strength connections. This paper presents the behavior of the partial strength of a non-composite beam-to-column connection for a cold-formed steel section where a gusset plate was used as a stiffener. This type of proposed connection for CFS is not limited only to the construction of roof trusses and wall cladding, but is also able to provide better flexural strength in semi-continuous construction. The proposed connections consisted of 6 specimens divided into two types, the first of which were stiffened by the gusset plate and the second of which were enhanced further with the top, seat and web angles. From the results of the experimental tests it was concluded that all the proposed connections can be categorized as partial strength connections, where the strength was more than 25% of the connected beam and suitable for use in semi-continuous construction. A relatively good agreement was recorded for the comparison between the experimental results and the predicted results from the EC3 component method super-imposed with a haunched gusset plate and top, seat and web angle components, which differed in the range of 1.31 to 1.5 times for the moment resistance and 1.07 to 1.37 times for the stiffness of the proposed connections.
UTILIZING RESPONSE SURFACE METHODS DESIGNS FOR OPTIMIZATION OF TECHNOLOGICAL PARAMETERS ON THE VIBRATION AMPLITUDE OF CNC ROUTER SPINDLE
Authors: Loc Nguyen Huu , Hung Nguyen Phuoc
Published: March 2021

For CNC machines, machining accuracy is of ultimate importance since it determines the quality of the products. Among many factors, vibration amplitude and stiffness are the key ones that influence the machining accuracy of a CNC machine. Remarkably, it is essential to conduct study into structural stiffness and the effect of technological parameters on the vibration amplitude of CNC router spindle with various second-order designs in order to improve machining accuracy. The research focuses on the application and comparison of the response-surface methods, the experimental research on the factors affecting the vibration amplitude, and the determination of the optimal working parameters for the CNC router.
COMPRESSION AND TENSION CREEP BEHAVIOUR OF LVL SENGON (PARASERIANTHES FALCATARIA)
Authors: Basuki Achmad , Awaludin Ali , Suhendro Bambang , Siswosukarto Suprapto
Published: March 2021

This study was aimed to investigate the creep behavior of laminated veneer lumber (LVL) Sengon,especially under the application of compression and tension stress parallel-to-the-grain. In IndonesiaLVL made from the fast-growing Sengon (Paraserianthes falcataria) species is designed to be usedas a substitution for solid wood in building construction. Creep test was conducted on the specimenswith reference to the ASTM D143‐09 standard test methods for small clear specimens of timber.Moreover, the constant loads were made equal to about 20%, 30%, and 40% of the 60% ultimateload derived from the static test and the creep test was conducted in a chamber having an averagetemperature of 25oC and minimum relative humidity of 65%. The results of creep test for a period of90 days showed that the creep factors were 0.51, 0.52, and 0.41, respectively for the specimens undertension stress level of 20%, 30%, and 40%, respectively. In the case of specimen under compressionstress parallel-to-the-grain, the creep factors were 0.42, 0.41, and 0.31, respectively, for stress levelequals to 20%, 30%, and 40%. It can be concluded that the creep factor under tension stress is slightlyhigher than that of specimens under compression stress, and these obtained creep factors are muchlesser than the values provided in the code.
ULTRASONIC PULSE VELOCITY TEST OF REINFORCED CONCRETE WITH INDUCED CORROSION
Authors: Ongpeng Jason Maximino Co
Published: March 2021

Non-destructive test has been applied to measure damage in structures. Common structures are assessed with the use of practical and easy application of ultrasonic pulse velocity (UPV). In this paper, the damage brought by corrosion was investigated using Proceq Punditlab having 54 kHz transducers oriented in direct transmission under the UPV. Fifty-four reinforced concrete of size 150 mm x 250 mm x 300 mm with two 10mm diameter reinforcing bars (Grade 40) and one 6mm diameter stainless steel bar (Type 304) was cast and tested. It had varying water cement ratio of 45%, 50%, and 55%with two conditions at day 0 (after curing), day 14, and day 28: non-accelerated condition under air-drying and accelerated condition using impressed current technique (ICT). The UPV test was conducted in each layer where reinforced steel bars were present and absent. It was found out that UPV test results was insignificant to all non-accelerated concrete, while it indicated significant damage for accelerated corrosion rate of more than 8 mm per year. In accelerated condition, the decrease in strength under UPV test was more than 20% for all specimens along the reinforced bars, and less than 15% for all specimens along the layer with no steel bars. This showed that the effect of corrosion greatly affects the entirety of structures near and far from the placement of reinforcing steel bars.
EFFECT OF VISCOSITY MODIFYING AGENTS ON DEWATERING UNDER PRESSURE AND THE PERFORMANCES OF MORTAR AND CONCRETE
Authors: Neupane Upendra , Julnipitawong Parnthep , Tangtermsirikul Somnuk , Yusuke Akino
Published: March 2021

This study emphasizes the effect of viscosity modifying agents (VMAs) on bleeding and dewatering of fresh mortars under high pressure. A detailed experimental dewatering device was designed and the analysis was carried out in order to evaluate the influence of two types of VMA on dewatering of freshly mixed mortars under high pressure. Additionally, the influence of the VMAs on mortar flow and air content of concrete was investigated. Two different types of VMA, which are a surfactant type and a starch ether type with various dosages were used in the tested mortar and concrete sample having the same water to binder ratio. Experimental results showed that by using dosages of surfactant type VMA equal to or higher than 3%, the pressurized dewatering of the mortars was significantly reduced. The use of starch in mortar mixtures was ineffective to reduce dewatering of mortars under high pressure. At same water to binder ratio, the addition of surfactant type VMA slightly increased the mortar flow and the v-funnel flow time due to enhancement of the air content in mixtures whereas starch ether decreased the mortar flow and increased the v-funnel time. The results of this study indicate that the surfactant type VMA is useful to control the dewatering of concrete under high pressure.
DIFFERENT PERCEPTIONS OF CONCERN FACTORS FOR STRATEGIC INVESTMENT OF THE PRIVATE SECTOR IN PUBLIC-PRIVATE PARTNERSHIP TRANSPORTATION PROJECTS
Authors: Sy Do Tien , Likhitruangsilp Veerasak , Onishi Masamitsu , Nguyen Phong Thanh
Published: March 2021

This paper identifies the concern factors of private investors associated with Public-Private Partnership (PPP) transportation projects in Vietnam. The concern factors are incorporated into four main groups: (1) company profile; (2) finance; (3) opportunities; and (4) risk perceptions. The paper examines the different perceptions by the public and private sectors about these concern factors adopted by experienced professionals related to PPP transportation projects. Based on a questionnaire survey in Vietnam, the most concern factors of private investors are their own capacity, demand issues, legal and political risks, long-term income, and financial sources issues of the PPP project. Moreover, five factors that represent the significant differences between the private and public sectors including political risks, enhancement of company’s strength in its industry, construction risks, demand issues, and financial viability of the company are also discovered. Addressing the different perceptions is indispensable to ensure the public sector can establish necessary policies that appeal to both domestic and foreign private investors. The paper at the same time hopes to provide some of lessons for the private sector.
PULSED ELECTRIC FIELD FOR PASTEURIZATION OF FRESH SUGARCANE JUICE
Authors: Trung Nguyen Duc , Hoang Nguyen Ngoc , Hieu Dang Minh
Published: March 2021

Pasteurization methods using pulsed electric fields (PEFs) have proved efficient at non-thermal inactivation of microorganisms and pathogens. The methods usually use a series of high intensity, narrow band electric fields that pass through target mediums where they induce irreversible damage to cellular membranes leading to the death of microorganisms by internal content loss breakage of cell homeostasis and other effects. This research proposed a simple, lab-scale PEF pasteurization equipment that uses common output electric voltages (220V and 110V, which provide electric power of 5.5 and 2.75 kV/m, respectively) with a simple designed Human-Machine Interface control. At a voltage of 110V, the equipment was tested with non-sterilized Czapek medium which showed more than 1.42-log reduction in the microbial density at 30s of the treatment and temperature below 60 o C. A test on suspended E. coli in modified Czapek medium also indicated an inactivation of most of bacterial cells after 40s of the treatment. We then applied the equipment to pasteurize fresh sugarcane juice and, as a result, the content of native microorganisms in sugarcane juice was reduced 1.2-log cycle, compared to that of original juice before the treatment.
MICROSTRUCTURAL, PHYSICAL AND MECHANICAL ANALYSIS OF RHA PORE MODIFIED POROUS ALUMINA WITH ALUMINUM AS REINFORCEMENT
Authors: Najib Mohamad Aznan Mohamad , Ariff Azmah Hanim Mohamed , Tahir Suraya Mohamad , As’arry Azizan , Mazlan Norkhairunnisa
Published: March 2021

Porous ceramics are being used in many industrial applications and processes that require extreme environment exposure due to its chemical inertness to corrosive medium and its ability to withstand high temperatures. Tailoring the porosity through pore modifier is one of the method available to ensure that the strength of ceramic is homogeneous. In order to improve the strength of the porous ceramic, the addition of aluminium powders was explored in this research. With the addition of agricultural waste source pore modifier and aluminium as reinforcement, the microstructure, linear shrinkage, porosity (open, closed and total), density, hardness and failure strength of this ceramic composite were examined. The ceramic composites were fabricated through powder metallurgy processing routes. Alumina, Al2O3 with the respective amounts of 0 to 10 wt.% (intervals of 10 wt.%) of RHA and 0 to 10 wt.% (intervals of 2 wt.%) of aluminum, Al, were mixed homogeneously with 12 wt.% of sucrose solution. The mixtures were compacted and heat-treated for 1 h at each of the soaking temperatures of 200°C, 600°C and 1000°C followed by full sintering at 1550°C for 2 h in a furnace. The results have shown that open and total porosity increases with increasing amounts of RHA and aluminum. Meanwhile, the linear shrinkage, close porosity, density, hardness and failure strength was reduced. In this research, the strength was expected to increase with the addition of aluminum. However, due to the increasing percentage of the total porosity with the increased addition of aluminum, the samples behave inversely. Phase transformations to mullite (3Al2O3. 2SiO2) were seen in this research with the addition of RHA. This phase formation helps to increase the overall strength of the ceramic composites, showing that 10 wt% addition of RHA have a positive impact, not only as a medium to modify the pore formation, but it also has a positive effect on the strength property of the ceramic composite.
SMART HOME AUTOMATION AND SECURITY SYSTEM DESIGN BASED ON IOT APPLICATIONS
Authors: Ahmad Shameem , Saha Arghya , Chek Leong Wen , Mekhilef Saad , Azam Tariful , Ahmed Mahrous , Orabi Mohamed , Ghoneim Sherif , Alharthi Mosleh , Alamri Basem
Published: March 2021

Conventional Home Automation Systems lack many of the essential properties of home automation system, which are now easily accessible with modern technologies like IoT where every device is connected and can be controlled through internet. The proposed system presents a standard home automation system with all requirements an automation system has like – scalable, configurable, DIY and serves the most important function which is plug and play. Firstly, this paper discuss the merits and demerits of mainstream works on home automation system. Next, key enabling technologies – Cloud (Pubnub), Android Applications, WiFi Module (ESP 8266), Raspberry Pi have been discussed. User interfaces for web, pc and mobile devices are designed for this system. Also, algorithm has been constructed for connecting Wi-Fi/Bluetooth module with the system to control wirelessly. Smart home security system has been added by using PIR motion Sensor. Lastly, data have been measured from the different sensors and power consumption of the devices were calculated and showed on a graph. . Then, electricity bill consumption has been calculated and sent by sms to the user. Global and local accessing from web interface and Android Application to control devices and configurable feature (change as per require) makes the system a standard home automation framework
Psychosocial risk factors for increased emergency hospital utilization by sickle cell disease patients: a systematic review protocol
Authors: Rech Jean-Simon , Getten Prunelle , Dzierzynski Nathalie , Lionnet François , Boëlle Pierre-Yves , Ranque Brigitte , Steichen Olivier
Published: March 2021

Objective:

To assess psychosocial risk factors for increased emergency hospital utilization by sickle cell patients.

Introduction:

Emergency hospital utilization by sickle cell disease patients is high but heterogeneous between patients and in a given patient over time. Psychosocial factors affect emergency hospital utilization and are a possible target to improve the management of sickle cell disease.

Inclusion criteria:

This review will include all original quantitative studies evaluating the impact of psychosocial risk factors on emergency hospital utilization by sickle cell disease patients. There will be no language restriction.

Methods:

PubMed, Embase, CINAHL, PubPsych, LiSSa, and Web of Science will be searched using a peer-reviewed search strategy. Study selection and extraction of data will be performed independently by two authors. Discrepancies will be solved by consensus or, if needed, by a third author. The authors will assess study quality, as well as perform a narrative synthesis of included studies, and where possible, meta-analyses with evaluation of heterogeneity and publication bias.

Systematic review registration number:

PROSPERO CRD42019140435.
Maintaining intravenous volume mitigates hypothermia‐induced myocardial dysfunction and accumulation of intracellular Ca2+
Authors: Nilsen Jan Harald , Schanche Torstein , Kondratiev Timofei V. , Hevrøy Olav , Sieck Gary C. , Tveita Torkjel
Published: March 2021

New Findings

What is the central question of this study?

Detailed guidelines for volume replacement to counteract hypothermia‐induced intravascular fluid loss are lacking. Evidence suggests colloids might have beneficial effects compared to crystalloids. Are central haemodynamic function and level of hypothermia‐induced calcium overload, as a marker of cardiac injury, restored by fluid substitution during rewarming, and are colloids favourable to crystalloids?

What is the main finding and its importance?

Infusion with crystalloid or dextran during rewarming abolished post‐hypothermic cardiac dysfunction, and partially mitigated myocardial calcium overload. The effects of volume replacement to support haemodynamic function are comparable to those using potent cardio‐active drugs. These findings underline the importance of applying intravascular volume replacement to maintain euvolaemia during rewarming.

Previous research exploring pathophysiological mechanisms underlying circulatory collapse after rewarming victims of severe accidental hypothermia has documented post‐hypothermic cardiac dysfunction and hypothermia‐induced elevation of intracellular Ca2+ concentration ([Ca2+]i) in myocardial cells. The aim of the present study was to examine if maintaining euvolaemia during rewarming mitigates cardiac dysfunction and/or normalizes elevated myocardial [Ca2+]i. A total of 21 male Wistar rats (300 g) were surface cooled to 15°C, then maintained at 15°C for 4 h, and subsequently rewarmed to 37°C. The rats were randomly assigned to one of three groups: (1) non‐intervention control (n = 7), (2) dextran treated (i.v. 12 ml/kg dextran 70; n = 7), or (3) crystalloid treated (24 ml/kg 0.9% i.v. saline; n = 7). Infusions occurred during the first 30 min of rewarming. Arterial blood pressure, stroke volume (SV), cardiac output (CO), contractility (dP/dtmax) and blood gas changes were measured. Post‐hypothermic changes in [Ca2+]i were measured using the method of radiolabelled Ca2+ (45Ca2+). Untreated controls displayed post‐hypothermic cardiac dysfunction with significantly reduced CO, SV and dP/dtmax. In contrast, rats receiving crystalloid or dextran treatment showed a return to pre‐hypothermic control levels of CO and SV after rewarming, with the dextran group displaying significantly better amelioration of post‐hypothermic cardiac dysfunction than the crystalloid group. Compared to the post‐hypothermic increase in myocardial [Ca2+]i in non‐treated controls, [Ca2+]i values with crystalloid and dextran did not increase to the same extent after rewarming. Volume replacement with crystalloid or dextran during rewarming abolishes post‐hypothermic cardiac dysfunction, and partially mitigates the hypothermia‐induced elevation of [Ca2+]i.
Comparison of Posterior Fixation Strategies for Thoracolumbar Burst Fracture: A Finite Element Study
Authors: Wong Chia-En , Hu Hsuan-Teh , Tsai Cho-Hsuan , Li Jun-Liang , Hsieh Chin-Chiang , Huang Kuo-Yuan
Published: March 2021

The management of thoracolumbar (TL) burst fractures remained challenging. Due to the complex nature of the fractured vertebrae and the lack of clinical and biomechanical evidence, currently, there was still no guideline to select the optimal posterior fixation strategy for TL burst fracture. We utilized a T10-L3 TL finite element model to simulate L1 burst fracture and four surgical constructs with one- or two-level suprajacent and infrajacent instrumentation (U1L1, U1L2, U2L1, and U2L2). This study was aimed to compare the biomechanical properties and find an optimal fixation strategy for TL burst fracture in order to minimize motion in the fractured level without exerting significant burden in the construct. Our result showed that two-level infrajacent fixation (U1L2 and U2L2) resulted in greater global motion reduction ranging from 66.0 to 87.3% compared to 32.0 to 47.3% in one-level infrajacent fixation (U1L1 and U2L1). Flexion produced the largest pathological motion in the fractured level but the differences between the constructs were small, all within 0.26 deg. Comparisons in implant stress showed that U2L1 and U2L2 had an average 25.3 and 24.8% less von Mises stress in the pedicle screws compared to U1L1 and U1L2, respectively. The construct of U2L1 had better preservation of the physiological spinal motion while providing sufficient range of motion reduction at the fractured level. We suggested that U2L1 is a good alternative to the standard long-segment fixation with better preservation of physiological motion and without an increased risk of implant failure.
Intervertebral Disc Mechanics With Nucleotomy: Differences Between Simple and Dual Loading
Authors: Yang Bo , Klineberg Eric , O'Connell Grace D.
Published: March 2021

Painful herniated discs are treated surgically by removing extruded nucleus pulposus (NP) material (nucleotomy). NP removal through enzymatic digestion is also commonly performed to initiate degenerative changes to study potential biological repair strategies. Experimental and computational studies have shown a decrease in disc stiffness with nucleotomy under single loading modalities, such as compression-only or bending-only loading. However, studies that apply more physiologically relevant loading conditions, such as compression in combination with bending or torsion, have shown contradicting results. We used a previously validated bone–disc–bone finite element model (Control) to create a Nucleotomy model to evaluate the effect of dual loading conditions (compression with torsion or bending) on intradiscal deformations. While disc joint stiffness decreased with nucleotomy under single loading conditions, as commonly reported in the literature, dual loading resulted in an increase in bending stiffness. More specifically, dual loading resulted in a 40% increase in bending stiffness under flexion and extension and a 25% increase in stiffness under lateral bending. The increase in bending stiffness was due to an increase and shift in compressive stress, where peak stresses migrated from the NP–annulus interface to the outer annulus. In contrast, the decrease in torsional stiffness was due to greater fiber reorientation during compression. In general, large radial strains were observed with nucleotomy, suggesting an increased risk for delamination or degenerative remodeling. In conclusion, the effect of nucleotomy on disc mechanics depends on the type and complexity of applied loads.
Non-Newtonian Blood Modeling in Intracranial Aneurysm Hemodynamics: Impact on the Wall Shear Stress and Oscillatory Shear Index Metrics for Ruptured and Unruptured Cases
Authors: Oliveira Iago L. , Santos Gabriel B. , Gasche José L. , Militzer Julio , Baccin Carlos E.
Published: March 2021

When simulating blood flow in intracranial aneurysms (IAs), the Newtonian model seems to be ubiquitous. However, analyzing the results from the few studies on this subject, the doubt remains on whether it is necessary to use non-Newtonian models in computational fluid dynamics (CFD) simulations of cerebral vascular flows. The objective of this study is to investigate whether different rheology models would influence the hemodynamic parameters related to the wall shear stress (WSS) for ruptured and unruptured IA cases, especially because ruptured aneurysms normally have morphological features, such as lobular regions and blebs, that could trigger non-Newtonian phenomena in the blood flow due to low shear rates. Using CFD in an open-source framework, we simulated four ruptured and four unruptured patient-specific aneurysms to assess the influence of the blood modeling on the main hemodynamic variables associated with aneurysm formation, growth, and rupture. Results for WSS and oscillatory shear index (OSI) and their metrics were obtained using Casson and Carreau–Yasuda non-Newtonian models and were compared with those obtained using the Newtonian model. We found that all differences between non-Newtonian and the Newtonian models were consistent among all cases irrespective of their rupture status. We further found that the WSS at peak systole is overestimated by more than 50% by using the non-Newtonian models, but its metrics based on time and surface averaged values are less affected—the maximum relative difference among the cases is 7% for the Casson model. On the other hand, the surface-averaged OSI is underestimated by more than 30% by the non-Newtonian models. These results suggest that it is recommended to investigate different blood rheology models in IAs simulations when specific parameters to characterize the flow are needed, such as peak-systole WSS and OSI.
Physics-Informed Neural Networks for Heat Transfer Problems
Authors: Cai Shengze , Wang Zhicheng , Wang Sifan , Perdikaris Paris , Karniadakis George Em
Published: March 2021

Physics-informed neural networks (PINNs) have gained popularity across different engineering fields due to their effectiveness in solving realistic problems with noisy data and often partially missing physics. In PINNs, automatic differentiation is leveraged to evaluate differential operators without discretization errors, and a multitask learning problem is defined in order to simultaneously fit observed data while respecting the underlying governing laws of physics. Here, we present applications of PINNs to various prototype heat transfer problems, targeting in particular realistic conditions not readily tackled with traditional computational methods. To this end, we first consider forced and mixed convection with unknown thermal boundary conditions on the heated surfaces and aim to obtain the temperature and velocity fields everywhere in the domain, including the boundaries, given some sparse temperature measurements. We also consider the prototype Stefan problem for two-phase flow, aiming to infer the moving interface, the velocity and temperature fields everywhere as well as the different conductivities of a solid and a liquid phase, given a few temperature measurements inside the domain. Finally, we present some realistic industrial applications related to power electronics to highlight the practicality of PINNs as well as the effective use of neural networks in solving general heat transfer problems of industrial complexity. Taken together, the results presented herein demonstrate that PINNs not only can solve ill-posed problems, which are beyond the reach of traditional computational methods, but they can also bridge the gap between computational and experimental heat transfer.
Thermal Transport in Polymers: A Review
Authors: Wei Xingfei , Wang Zhi , Tian Zhiting , Luo Tengfei
Published: March 2021

In this article, we review thermal transport in polymers with different morphologies from aligned fibers to bulk amorphous states. We survey early and recent efforts in engineering polymers with high thermal conductivity by fabricating polymers with large-scale molecular alignments. The experimentally realized extremely high thermal conductivity of polymer nanofibers is highlighted, and understanding of thermal transport physics is discussed. We then transition to the discussion of bulk amorphous polymers with an emphasis on the physics of thermal transport and its relation with the conformation of molecular chains in polymers. We also discuss the current understanding of how the chemistry of polymers would influence thermal transport in amorphous polymers and some limited, but important chemistry-structure-property relationships. Lastly, challenges, perspectives, and outlook of this field are presented. We hope this review will inspire more fundamental and applied research in the polymer thermal transport field to advance scientific understanding and engineering applications.
Homogeneous and Automated Cooling of a Mold Segment by Multiple Water Jet Impingement and a Cross Air Flow
Authors: Agyeman Emmanuel K. K. , Mousseau Pierre , Sarda Alain , Edelin Denis , Lecointe Damien
Published: March 2021

Multiple water jets and a cross air flow are used to cool a mold segment in a homogeneous and automated manner. The test segment was cooled from an initial temperature of 573 K. An average temperature difference of less than 3 K and a maximum temperature difference of less than 6 K were obtained along the length of the surface of the test segment during the entire duration of the cooling process as opposed to the traditional channel cooling approach where the mean and maximum temperature differences increase over time. The top surface of the test segment represents the mold/part interface which is of interest in this study. Using model predictive control (MPC) and a data-driven predictive model, the cooling speed of the test segment’s top surface was able to be maintained within ±5 K of the cooling ramp imposed. The results were compared to the results obtained when using a simpler On/Off algorithm for automated cooling. Compared to the simpler On/Off algorithm, there was an improvement in the accuracy of the cooling ramp with respect to its reference value of over 30% for most cooling ramps tested (5–25 K/min). A parametric study on the influence of the flowrates of the fluids on the cooling speed of the test segment’s surface was also conducted.
Closure to “Computational Analysis for Mixed Convective Flows of Viscous Fluids With Nanoparticles” (Farooq, U., Lu, D. C., Ahmed, S., and Ramzan, M., 2019, ASME J. Therm. Sci. Eng. Appl., 11(2), p. 021013)
Authors: Cui Jifeng , Farooq Umer , Razzaq Raheela , Khan Waseem Asghar , Yousif Mogtaba Ahmed
Published: March 2021

The authors regret in the published paper referenced above and agree with the discussion by Pantokratoras (2019, “Discussion: “Computational Analysis for Mixed Convective Flows of Viscous Fluids With Nanoparticles” (Farooq, U., Lu, D. C., Ahmed, S., and Ramzan, M., 2019, ASME J. Therm. Sci. Eng. Appl., 11(2), p. 021013),” ASME J. Therm. Sci. Eng. Appl., 11(5), p. 055503). In this Closure, the non-similar mathematical model is developed to describe the mixed convective nanofluid flow over vertical sheet which is stretching at an exponential rate. In the published article referenced above, similarity transformations are utilized to convert the governing nonlinear partial differential equations (PDEs) into ordinary differential equations (ODEs). The important physical numbers such as magnetic field (M2), Brownian motion parameter (Nb), thermophoresis (Nt), Eckert number (Ec), ratio of mass transfer Grashof to heat transfer Grashof (N), buoyancy parameter (λ), and Reynolds number (Re) appearing in the dimensionless ODEs are still functions of coordinate “x”; therefore, the problem is non-similar. In this corrigendum, the non-similar model is developed by using ξ(x) as non-similarity variable and η(x, y) as pseudo-similarity variable. The dimensionless non-similar model is numerically simulated by employing local non-similarity via bvp4c. The graphical results show no change in behavior. The important thermal and mass transport quantities such as Nusselt number and Sherwood number have been computed for the non-similar model, and results are compared with the published article.
Measurement and Evaluation of the Stiffness Characteristics of Precision Spring Tubes in Hydraulic Servovalves
Authors: Zhang Fuli , Yuan Zhaohui
Published: March 2021

The spring tube is the core component of the hydraulic servovalve, and its stiffness characteristics determine the sensitivity of the servovalve. For the difficulty in measuring and ensuring the stiffness of spring tube in complex structures, based on the principle of structural characteristics and stiffness measurement, an effective method for measuring and evaluating the stiffness of spring tube was proposed. First, by the force analysis of the spring tube in the valve structure, using improved stiffness measurement theory, an equivalent measurement model of single-arm is established. Second, the stiffness measurement system of the spring tube is constructed based on this model. Furthermore, using the deformation and the spatial position recurrence method, the accuracy of the measurement system is further improved. Thirdly, using the orthogonal test method and linear optimization method of the neural network model, the stiffness characteristics of the spring tube under the influence of different factors are studied further. Finally, the validity of the models is verified by using the software comsol and the experimental platform. The stability of the effective stiffness for the spring tube is further analyzed by the measurement data. The contribution and novelty of this paper are that based on the force analysis of the spring tube in the servovalve internal structure, an effective and systematic stiffness measurement and evaluation method are proposed. On this basis, experiments and stiffness characteristics analysis are carried out. Furthermore, several structural factors affecting the stiffness characteristics of spring tube are considered, and the stiffness characteristics of spring tube are systematically studied and analyzed. Based on this research and analysis, the systematic study of measurement and characteristics of precision components is very important for practical complex systems in this field. This makes it possible to further study the measurement of precision components which are difficult to measure in the actual structure. It is instructive to study the characteristics of precision components in complex structures.
An Intelligent Predictive Controller for Power and Battery Management in Plug-In Hybrid Electric Vehicles
Authors: Hassanzadeh Mojtaba , Rahmani Zahra
Published: March 2021

This paper presents a novel real-time energy management strategy (EMS) for plug-in hybrid electric vehicles (PHEVs), which combines the adaptive neuro-fuzzy inference system (ANFIS) and the model predictive control (MPC). A two-objective EMS with two state variables is defined by integrating the battery aging and fuel economy in the objective function. First, the dynamic programming (DP) approach is applied offline to obtain the globally optimal solutions. Then, a real-time predictive EMS is proposed, in which DP carries out a moving-horizon optimization. Contrary to the charge-sustaining HEVs, the optimal trajectory of the battery state-of-charge (SOC) in PHEVs does not fluctuate around a constant level. Thus, determining the desired value of SOC for the real-time moving-horizon optimization is a challenging issue. Unlike the EMSs with a pre-determined reference for SOC, a trained ANFIS model constructs the real-time sub-optimal SOC trajectory in advance. Finally, the effectiveness of the proposed approach is shown through simulation. The proposed EMS is examined over multiple real-time driving cycles, and the results indicate that the total cost is increased compared to those unaware of battery aging. The real-time EMS is then compared to different approaches. While suboptimal, the proposed EMS is real-time implementable, and the results are found to be close enough to those of optimal controller, compared to the two other tested approaches.
Pyroelectric lithium niobate electron emission-based ion-pump
Authors: Vinayakumar KB , Gund Ved , Lal Amit
Published: March 2021

This work presents a compact ion-pump that utilizes pyroelectricity for ionization of ambient molecules. The pyroelectric ionization is realized by heating a lithium niobate (LiNbO3) crystal with low voltage resistive heating (10 V drive voltage, 0.5 W Joule heating) to generate a high voltage across the poled surface of the crystal. Pyroelectrically generated electrons from the polarized surface of the crystal are accelerated using an electric field generated by both the crystal and external titanium (Ti) electrodes biased at ±300 V, which results in the ionization of molecules in the chamber. The low collector current in the pA range ensures that the power consumed due to ionization current is lower than the LiNbO3 heating power. The ionized gas molecules are accelerated toward the Ti collector electrodes where they are implanted owing to large acceleration produced by the collector electrodes. The system is configured as a sputter pump for gettering ions to reduce chamber pressure from the baseline value of 1.4 μTorr with just the external pump to 1.1 μTorr by incorporating the LiNbO3 pump. The proof-of-concept of the pyroelectric pumping mechanism is demonstrated using a 140 cm3 stainless steel vacuum chamber, with supplementary turbomolecular and diaphragm pumps and demonstrates that a 50 s thermal cycling of the crystal is optimal for the ion-pump. Pumping action was measured with a Pirani gauge and a hot cathode ion gauge. Analytical modeling and experimental results for pumping speed calculations showed a good match during high-pressure pumping.
The differential effects of vowel and onset consonant lengthening on speech segmentation: Evidence from Taiwanese Southern Min
Authors: Ou Shu-chen , Guo Zhe-chen
Published: March 2021

A review of previous speech segmentation research suggests the prediction that listeners of Taiwanese Southern Min (TSM), a lexical tone language, would exploit vowel lengthening and syllable-onset consonant lengthening to locate word ends and beginnings, respectively. Yet, correlations between segment duration and tone identity in tone languages along with some TSM-specific phonological phenomena may work against such use. Two artificial language learning experiments examined TSM listeners' use of the lengthening cues. The listeners heard the words of an artificial language (e.g., /ba.nu.me/) repeated continuously and identified them in a subsequent two-alternative forced-choice test. Experiment I revealed that their segmentation benefits from and only from word-initial onset lengthening or word-final vowel lengthening, supporting the prediction. Experiment II further demonstrated that these two cues in combination synergistically support segmentation at least when compared to word-initial onset lengthening alone, consistent with previous findings regarding complementary cues. These results furnish additional evidence that vowel and onset consonant lengthening affect segmentation in different ways, possibly reflecting a functional division between vowels and consonants that is supported by some prosody-computing mechanism. Additionally, vowel lengthening seems to affect segmentation to a greater extent than onset consonant lengthening. Possible explanations for this and further issues are discussed.