bluuebunny/crossref_metadata_2025 huggingface dataset:
Arthroscopic Tenodesis of the Long Head of the Biceps
Authors: Harwin Steven F. , Birns Michael E. , Mbabuike Jean-Jacques , Porter David A. , Galano Gregory J.
Published: October 2014

The long head of the biceps (LHB) is commonly implicated in shoulder pathology due to its anatomic course and intimacy with the rotator cuff and superior labrum of the glenoid. Treatment of tendinosis of the LHB may be required secondary to partial thickness tears, instability/subluxation, associated rotator cuff tears, or SLAP (superior labrum, anterior to posterior) lesions. Treatment options include open or arthroscopic techniques for tenodesis vs tenotomy. Controversy exists in the orthopedic literature regarding the preferred procedure. The all-arthroscopic biceps tenodesis technique is a viable and reproducible option for treatment. This article provides a review of the all-arthroscopic biceps tenodesis technique using proximal interference screw fixation and its subsequent postoperative regimen. All-arthroscopic biceps tenodesis maintains elbow flexion and supination power, minimizes cosmetic deformities, and leads to less fatigue soreness after active flexion. Thus, arthroscopic biceps tenodesis should be offered and encouraged as a treatment option for younger, active patients. [
Orthopedics
. 2014; 37(11):743–747.]
Repair of Tibialis Anterior Muscle Herniation Using Periosteum
Authors: Harwin Steven F. , Choi Young-Rak , Hong Chul-Gie
Published: October 2014

Muscular herniation consists of focal muscular protrusions through an acquired or congenital fascial defect. The anterior tibialis muscle is most frequently affected. Asymptomatic muscle hernias are usually treated conservatively. For severe symptoms or cosmetic complaints, several surgical techniques are available to treat muscle herniation, including fasciotomy, fascial patch grafting using autologous fascia lata, or synthetic mesh. However, the optimal surgical approach remains debatable. The authors propose a novel and reproducible surgical method using a periosteal turn-down technique. This surgical technique has the advantages of fewer complications, greater cost-effectiveness, and high reproducibility. The authors find this to be a useful technique. [
Orthopedics.
2014; 37(11):748–750.]
Radiographic Evidence of Anterior Cruciate Ligament Insufficiency
Authors: Johnson Darren L. , Brunkhorst Joseph , Johnson Darren L.
Published: October 2014

Anterior cruciate ligament (ACL) tears are commonly seen injuries. Initially, these injuries are routinely evaluated with radiographs, followed by magnetic resonance imaging (MRI). The altered kinematics at the time of injury or for the duration of a chronic tear can create indirect findings on radiographs and MRI. These signs may help establish a diagnosis of an ACL tear or the chronicity of the injury. This article discusses these signs. [
Orthopedics.
2014; 37(11):759–762.]
A Systematic Review and Adjusted Indirect Comparison of Oral Anticoagulants
Authors: Cui Juncheng , Wu Bei , Liu Congwei , Li Zhihong
Published: October 2014

Educational objectives

As a result of reading this article, physicians should be able to:

1.

Recognize the high risk of postoperative venous thromboembolism (VTE) in patients undergoing major orthopedic surgery.

2.

Distinguish the different pharmacological mechanisms of VTE prophylaxis drugs.

3.

Delineate the advantages and disadvantages of each VTE prophylaxis drug.

4.

Recognize that rivaroxaban is as efficacious as apixaban but can increase the risk of hemorrhage.

Patients undergoing major orthopedic surgery are at high risk for developing postoperative venous thromboembolism (VTE). The authors analyzed the available evidence on the efficacy and safety of dabigatran, apixaban, and rivaroxaban vs low-molecular-weight heparins (LMWHs) as VTE prophylaxis in major orthopedic surgery. Outcomes evaluated included total VTE, deep venous thrombosis (DVT), pulmonary embolism (PE), death, and major bleeding. Rivaroxaban and apixaban are more efficacious than dabigatran and are as safe as dabigatran. Rivaroxaban is as efficacious as apixaban but can increase the risk of hemorrhage. [
Orthopedics.
2014; 37(11):763–771.]
Prevalence of Rotator Cuff Tears in Operative Proximal Humerus Fractures
Authors: Choo Andrew , Sobol Garret , Maltenfort Mitchell , Getz Charles , Abboud Joseph
Published: October 2014

Proximal humerus fractures and rotator cuff tears have been shown to have increasing rates with advancing age, theoretically leading to significant overlap in the 2 pathologies. The goal of this study was to examine the prevalence, associated factors, and effect on treatment of rotator cuff tears in surgically treated proximal humerus fractures. A retrospective review was performed of all patients who had surgery for a proximal humerus fracture from January 2007 to June 2012 in the shoulder department of a large academic institution. Patient demographics, the presence and management of rotator cuff tears, and surgical factors were recorded. Regression analysis was performed to determine which factors were associated with rotator cuff tears. This study reviewed 349 fractures in 345 patients. Of these, 30 (8.6%) had concomitant rotator cuff tears. Those with a rotator cuff tear were older (average age, 68.7 vs 63.1 years), were more likely to have had a dislocation (40% vs 12.5%), and were more likely to have undergone subsequent arthroscopic repair or reverse total shoulder arthroplasty than those without a rotator cuff tear. Most (22 of 30) were treated with suture repair at the time of surgery, but 5 patients underwent reverse total shoulder arthroplasty based primarily on the intraoperative finding of a significant rotator cuff tear. A concomitant rotator cuff tear in association with a proximal humerus fracture is relatively common. Rotator cuff tears are associated with older patients and those with a fracture-dislocation. In rare cases, these cases may require the availability of a reverse shoulder prosthesis.
Hardware-Related Complications After Dorsal Plating for Displaced Distal Radius Fractures
Authors: Matzon Jonas L. , Kenniston Julia , Beredjiklian Pedro K.
Published: October 2014

There has been a trend away from dorsal fixation of distal radius fractures secondary to a historically higher complication rate. However, the literature on low-profile dorsal plates and titanium implants for the treatment of these fractures is limited. The goal of the current study was to evaluate hardware-related complications and removal rates after open reduction and internal fixation of unstable, displaced distal radius fractures using a dorsal approach with a low-profile titanium plate. A single surgeon treated 125 patients with isolated, unstable, dorsally displaced distal radius fractures by open reduction and internal fixation using a low-profile titanium dorsal plating system. A total of 110 patients were followed for a minimum of 1 year, and mean follow-up was 27 months (range, 12–74). Outcomes were assessed radiographically and clinically. Satisfactory alignment was achieved in all cases, and no fracture went on to nonunion. Nine patients (8%) required removal of hardware at an average of 12 months (range, 6–34). Six patients (5%) had evidence of extensor tenosynovitis intraoperatively, but no extensor tendon ruptures were identified. Overall, using the Gartland and Werley score, results were excellent in 82 patients, good in 22 patients, fair in 5 patients, and poor in 1 patient. Six complications accounted for the fair and poor results. The average Disabilities of the Arm, Shoulder and Hand (DASH) score at latest follow-up was 6 (range, 0–25). This series showed that the technique of dorsal plating with a low-profile titanium plate is safe and effective.
Drug Elution From High-Dose Antibiotic-Loaded Acrylic Cement: A Comparative, In Vitro Study
Authors: Gasparini Giorgio , De Gori Marco , Calonego Giovanni , Bora Tommaso Della , Caroleo Benedetto , Galasso Olimpio
Published: October 2014

High-dose antibiotic-loaded acrylic cement (ALAC) is used for managing peri-prosthetic joint infections (PJIs). The marked increase in resistant high-virulence bacteria is drawing the attention of physicians toward alternative antimicrobial formulations loaded into acrylic bone cement. The aim of this in vitro study was to determine the elution kinetics of 14 different high-dose ALACs. All ALAC samples showed a burst release of antibiotics in the first hour, progressively decreasing over time, and elution curves strictly adhered to a nonlinear regression analysis formula. Among aminoglycosides, commonly seen as the most appropriate antibiotics to be loaded into the bone cement, the highest elution rate was that of tobramycin. Among the glycopeptides, a class of antibiotics that should be considered to treat PJIs because of the prevalence of aminoglycoside resistance, vancomycin showed better elution than teicoplanin. Clindamycin, which can be associated with aminoglycosides to prepare ALACs and represents a useful option against the most common pathogens responsible for PJIs, showed the highest absolute and relative elutions among all the tested formulations. A noticeable elution was also detected for colistin, an antibiotic of last resort for treating multidrug-resistant bacteria. The current study demonstrates theoretical advantages in the preparation of ALAC for some antibiotics not routinely used in the clinical setting for PJIs. The use of these antibiotics based on the infecting bacteria sensitivity may represent a useful option for physicians to eradicate PJIs. In vivo testing should be considered in the future to confirm the results of this study.
Initial Experiences With a New MRI Scoring System for Differentiating Advanced Femoral Osteonecrosis From Tubercular Arthritis
Authors: Venugopal Vasanthakumar , Prabhu Alex Daniel , Afshan Ishrat , Haider Mehvash , Ullah Ekram
Published: October 2014

The purpose of this study was to formulate a magnetic resonance imaging–based scoring system for differentiating tuberculous arthritis from advanced osteonecrosis of the femoral head. Magnetic resonance imaging findings in 18 hips with tuberculous arthritis and 36 hips with advanced osteonecrosis of the femoral head were reviewed retrospectively. Confirmation of tuberculous arthritis was based on enzyme-linked immunosorbent assay and/or synovial biopsy. Osteonecrosis was confirmed either by histopathology or eventual radiographic evidence on follow-up. The findings were analyzed with an emphasis on the changes in femoral head marrow, joint cavity, synovium, acetabulum, and contrast enhancement patterns. A score of 2 was assigned for the presence of each of the following: T2 hyperintensity of the femoral head, synovial hypertrophy, articular cartilage erosion, unilateral involvement of the femoral head, acetabular edema/sclerosis, and enhancement of the involved head. A score of 1 was assigned for each of the following: joint effusion, edema of adjacent marrow, and enhancement of adjacent soft tissue. A cutoff value of 10 of 15 points was considered to be positive for tuberculous arthritis. Sixteen of 18 cases of tuberculous arthritis were correctly identifiable on the basis of this scoring system. The 2 remaining cases had a score of 9. No case of osteonecrosis of the femoral head scored more than 9. A score of 10 for a positive diagnosis of tuberculous arthritis had a sensitivity of 88.89% and specificity of 100%. Positive and negative predictive values were 1 and 0.94, respectively. Statistical significance for each of the parameters and the entire model was established with logistic regression analysis. This new scoring system is effective in solving the imaging dilemma pertinent to endemic regions.
Maisonneuve-Hyperplantarflexion Variant Ankle Fracture
Authors: Hinds Richard M. , Tran Wesley H. , Lorich Dean G.
Published: October 2014

Maisonneuve fractures are rare ankle injuries, accounting for up to 7% of all ankle fractures. They consist of a proximal third fibula fracture, syndesmotic disruption, and medial ankle injury (either a deltoid ligament disruption or a medial malleolus fracture), and are often successfully managed with nonoperative treatment of the proximal fibula fracture and open reduction and internal fixation (ORIF) of the medial ankle injury and syndesmotic disruption. The hyperplantarflexion variant ankle fracture comprises approximately 7% of all ankle fractures and features dual posterior tibial lip fractures featuring a posterolateral fragment and a posteromedial fragment. Good functional results have been reported in the literature after ORIF of both the posterolateral and posteromedial fragments of this variant fracture that is not described by the Lauge-Hansen classification. In this report, the authors present the unique case of an isolated ankle fracture demonstrating characteristics of both a Maisonneuve fracture and a hyperplantarflexion variant ankle fracture. They also highlight the diagnostic imaging characteristics, including magnetic resonance imaging (MRI) and preoperative radiograph findings, surgical treatment, and postoperative clinical outcome for this patient with a Maisonneuve-hyperplantarflexion variant ankle fracture. To the authors’ knowledge, this unique fracture pattern has not been reported previously in the literature. The authors conclude that although good results were seen postoperatively in this case, the importance of ORIF of both the posteromedial and posterolateral fragments of variant fractures cannot be overstated. They also found MRI to be a particularly helpful adjunct in formulating the correct diagnosis and treatment plan.
The Masquelet Procedure Gone Awry
Authors: Assal Mathieu , Stern Richard
Published: October 2014

The Masquelet technique was first performed in 1986. It is a 2-stage procedure for healing of substantial bone defects, with or without the presence of infection. In the former situation, a thorough debridement of the infected site is necessary to achieve a clean cavity. A cement block is fashioned to fit into the entire defect to act as a spacer that maintains the space for grafting and reconstruction and induces a synovial-like membrane. The induced membrane avoids resorption of the bone graft and secretes growth factors, including vascular and osteoinductive factors, to promote revascularization of the graft. The membrane has an inner part that is a synovial-like epithelium and an outer part composed of fibroblasts, myofibroblasts, and collagen. It is richly vascularized. After a period of 6 to 8 weeks, the spacer is removed by incising the induced membrane that has formed. Copious bone graft, usually autologous and obtained from the iliac crest or by other means, is placed into the defect that is now lined by the induced membrane. The membrane is closed over the graft. This article describes a young patient who started on the correct path for a Masquelet procedure only to have it turn in the wrong direction. However, the problem was not recognized until 8 years after the initial injury. The situation was corrected by performing the final stage of the procedure as it was originally described.
Knowledge Assets Management in the Energy Industry
Authors: Lerro Antonio , Schiuma Giovanni , Jacobone Francesca A.
Published: October 2014

The purpose of this chapter is to examine the state-of-the-art of Knowledge Assets Management (KAM) in the energy industry, reviewing both the literature and the practice of KAM initiatives. Particular attention is provided to the renewable energy sector and to the Small and Medium Enterprises (SMEs). It emerges that most of the literature is focused on big companies and little attention is paid to the renewable energy sector. It emerges that some organizations, especially in the oil industry, are seen as leaders in KM practice. On the other hand, SMEs operating in the renewable energy industry are not aware of the relevance of KAM and then do not address explicitly KAM initiatives or projects. The research reveals that small firms do indeed manage knowledge assets informally as part of their normal activities, without using the terminology and concepts of knowledge management discipline.
Self-Organization as a Perspective for Organizational Learning
Authors: Blomme Robert J.
Published: October 2014

This chapter introduces the perspective of self-organization for organizational learning. Using the perspective of organizations as actor networks in which common activities are established through the connected behaviour of individual actors, it argues that organizational learning entails altered and different behaviour on the part of actors, leading to alterations in the ways in which individual behaviour is interconnected. Organizational learning is fuelled by ambiguity perceived by the organization's actors who try to make “sense” of their surroundings, when they observe it, grapple with it, grasp it, and manipulate it. In this chapter, the author elaborates on the implications of this perspective for organizational learning and the learning practitioner in the role of leader.
How Does the Hierarchical Management System Influence the Climate of Creativity in Chinese University Laboratories?
Authors: Zhou Chunfang
Published: October 2014

This chapter aims to investigate how the Chinese hierarchical management system influences the climate of creativity in university laboratories. A questionnaire (Creative Climate Questionnaire, CCQ) survey was carried out with 25 laboratories (126 participants) at 7 universities in Northeastern China. The comparative study reveals both the advantages and disadvantages of the hierarchical management system for creativity in university laboratories. To some extent, the hierarchical system stimulates different levels of laboratories to shape different collective objectives and goals, and it increases the synergy of the creative abilities of group members in laboratories. However, the uniform model of “hard resource distribution” regulated by the hierarchical system cannot meet the diverse needs for the development of creativity in university laboratories.
Knowledge Sharing Barriers in Procurement
Authors: Atkova Irina , Tuomela-Pyykkönen Marika
Published: October 2014

This chapter introduces knowledge management as a means to analyse the process of knowledge sharing in organisations, specifically knowledge-sharing barriers faced by companies in procurement on the level of an individual employee, as well as at the level of an organisation. It argues that at the individual level knowledge sharing process is frequently hoarded by internal resistance, lack of trust, insufficient motivation, gap in awareness and knowledge, and at the organizational level, by bureaucracy and hierarchy, paradigm incoherency, lack or organisational reciprocity, absence of common legitimate language, organisational and national cultures, competition between the business units and departments, poor communication infrastructure, and localization. The chapter does not aspire to provide a complete list of the knowledge-sharing barriers faced by the companies within procurement but instead to draw attention to the complexity and problematic of the knowledge-transfer process. Awareness of the potential knowledge-sharing barriers allows the managers and companies to proactively respond to these challenges and develop solutions for a specific organisation.
Strategic Tacit Knowledge-Based Competitiveness
Authors: Tamzini Khaled
Published: October 2014

By using the resource-based view as a theoretical framework, the purpose of this chapter is to explain the internal sources of competitiveness in Tunisian firms operating in the industry of Information Communication and Technology (ICT). In other words, how do firms within this industry build their competitive advantage and performance? Based on the results of the academic research undertaken in 2012 on a sample of 209 Tunisian ICT firms, the author explains how strategic tacit knowledge (seen as strategic resource) allows the firms to gain a sustainable competitive advantage and superior performance. In addition, it provides researchers with an empirical method to operationalize tacit knowledge appropriately, as well as competitive advantage and performance. It also focuses on the exploration of the relationship between these three variables, demonstrating that competitive advantage mediates the impact of tacit knowledge on performance. Finally, this chapter is considered an attempt to respond to criticism formulated against the resource-based view.
Developing a Framework of Human Resource Management, Organizational Learning, Knowledge Management Capability, and Organizational Performance
Authors: Kasemsap Kijpokin
Published: October 2014

This chapter introduces the framework and the practical concepts of Human Resource Management (HRM), organizational learning, Knowledge Management Capability (KMC), and organizational performance. This chapter also explains the role of HRM, organizational learning, and KMC on organizational performance. The developed framework presents the relationship among the constructs (i.e., HRM, organizational learning, KMC, and organizational performance) and contributes toward a better understanding of the specific mechanisms through which HRM, organizational learning, and KMC positively influence organizational performance. HRM effectively acts as a trigger toward effective organizational learning and KMC processes, thus creating a valuable organizational performance. Organizational performance that can usually help to perform a task in an integrated manner is a source of sustainable competitive advantage. Understanding the role of HRM, organizational learning, KMC, and organizational performance through the framework will significantly enhance the organizational performance and achieve business goals in the modern business world.
How to Capitalize Knowledge within Online Communities
Authors: Berkani Lamia , Chikh Azeddine
Published: October 2014

Social media has become a rising trend, creating new ways of collaboration, competition, and interaction between people, such as creation exchange and sharing of ideas and knowledge. However, one of the problems encountered is the organization of the knowledge capitalization process in order to facilitate knowledge access and reuse. The authors focus in this chapter on online communities and how they try to help their members to capitalize their knowledge. The authors propose a model for knowledge creation based on both the Nonaka's SECI model and an empirical model of questioning called the six Ws (Who, What, Where, When, Why, and How). A case study related to a higher education community made up of teachers in computer science is presented, and the main results are discussed.
Influences of Factors of Human Resources for Innovation in Services Companies
Authors: Mazini Sergio Ricardo , Ulian Elisângela
Published: October 2014

The chapter aims to understand how human factors influence and contribute to have an organizational climate conducive to creativity and innovation in service companies. The chapter also proposes an analytical framework to assess the influence of human resources, and understanding how they contribute to that has a climate conducive to innovation. The proposed methodology is the multiple case study and qualitative research in Brazilian companies. The analyses and discussions identify that conducting innovative decentralized actions may harm the process, and efficient management practices, such as the use of collaborative work, skills assessment, and identification of technology trends, assist in the innovation process.
SME Succession Planning and Knowledge Loss Assessment
Authors: Durst Susanne , Yip Jessica , Lee Rongbin W. B.
Published: October 2014

The aging workforce will soon lead to a number of retirements in Small and Medium-Sized Enterprises (SMEs) that cannot be compensated for by the decreasing pool of succeeding individuals. Consequently, SMEs need to find ways to cope with the demographic challenge and its possible consequences. Otherwise, its capability to act is at risk in situations when critical staff is leaving. This clearly illustrates the need for a proper succession planning. One that takes into consideration the knowledge at stake. The aim of this chapter is to draw attention to the danger of knowledge loss as a consequence of an aging workforce and to discuss three approaches SMEs can use to better understand the knowledge at risk. Set against the importance of SMEs in most of the world, the study´s results provide relevant insights into how to cope with knowledge at risk in order to secure the firms´ survivability.
Computational Exploration of a Two-Spool High Bypass Turbofan Engine's Component Deterioration Effects on Engine Performance
Authors: Awang Saifudin Awang Raisudin , Mazlan Nurul Musfirah
Published: October 2014

Aircraft engines are exposed to degradation due to several factors such as environmental air pollution, fuel content and ageing or degradation of engine’s components, which are experienced within specified time. While the turbofan in operation, its components deteriorate and consequently affect its performance. This study is aimed to computationally investigate the effect of components degradation on engine performance. A high bypass turbofan engine operated at cruise is selected for this evaluation and the simulation was performed using the Gas Turbine Simulation Program (GSP). The affected components considered are turbines and compressors with deterioration rate ranging from 0% to 5%. The effect of selected deterioration rate on engine thrust and thrust specific fuel consumption (TSFC) is studied. Results obtained show an agreement with literature where reduction in engine thrust and TSFC are observed. Turbine’s fouling has been found to be more severe than erosion in terms of power and efficiency losses. However, in terms of the overall performance, the erosion effect is more severe than fouling.
CFD Validation and Analysis of a Single-Stage Axial Compressor
Authors: Xiang Jun Ting , Schlüter Jӧrg Uwe , Duan Fei
Published: October 2014

The knowledge about changes of flow field properties during axial compressor operationat high and relatively low speed is limited. This work provides a numerical approach to addressthese problems. Validations about the numerical scheme and the test of compressor performance at various operating speeds are conducted. The results show that computational fluid dynamics (CFD)is capable in predicting the compressor performance. Flow property changes during the compressoroperation are discussed and explanations are proposed. This work reinforces the understanding of compressor operation and provides valid results for future reference.
Spray Characteristics of an Internal-Mix Airblast Atomizer
Authors: Chong Cheng Tung , Hochgreb Simone
Published: October 2014

Detailed characterisation of spray atomization of an injector is important for combustor design and modelling. In this paper, the effects of air/fuel mass ratio on the spray characteristics of an internal-mix airblast atomizer were examined. Distribution of the spatial mean droplet axial velocity and size were measured simultaneously using a phase Doppler anemometry (PDA). In general, small droplets are distributed at the center of the spray with maximum velocity. The droplet size increases with increasing radial distance from the spray centreline, but the drop velocity decreases to a minimum at the spray edge. Increasing the atomizing air/fuel mass ratio reduces fuel droplet size due to increased shear.
Development of Blimp Platform for Aerial Photography
Authors: Jo Hudyjaya Siswoyo , Tsun Mark Tee Kit , Yoong Carmella Sim Lee
Published: October 2014

This paper presents the development of a semi-automated blimp platform for aerial photography. The blimp can be tele-operated from a ground station and is capable of autonomously holding its heading and altitude when the pilot releases control. The blimp consists of a helium-filled envelope to achieve the buoyancy and a pair of propellers to drive the blimp in the desired direction. A basic control algorithm and sensing system are also proposed to control and maintain the heading and altitude of the blimp.
Experimental Study on the Effect of Skin Flexibility on Aerodynamic Performance of Flapping Wings for Micro Air Vehicles
Authors: Yusoff Hamid , Abdullah Mohd Zulkifly , Ahmad Kamarul Arifin , Abdullah M.K. , Suhaimi Shafiq
Published: October 2014

In the present study, the aerodynamic characteristics such as time-averaged lift and drag generation of two flexible membrane (latex thin and thick) wings with different skin flexibilities are compared with those of a conventional rigid (wood) wing to assess the effects of skin flexibility (rigidity) on the aerodynamic performance for flapping flight applications. The experiments are performed in an open circuit wind tunnel of non-return airflow with a test section of (0.3m x 0.3m) and is capable of speeds from 0.5 to 30 m/s. The time-averaged lift and drag as functions of flapping frequency, forward flight velocity and the orientation angle of the flapping motions with respect to the incoming flows are measured by using a strain gauge balance and KYOWA PCD-300A sensor interface data acquisition system. It has been found that flapping motion would bring significant aerodynamic benefits when the flapping flight is in unsteady state regime, with advance ratio less than 1.0. The aerodynamic benefits are found to decay exponentially with the increasing advance ratio. Flapping motion is found to become detrimental for high speed flight applications. It is also observed that the skin flexibility has considerable effect on the aerodynamic performance. The flexible latex thick wing is found to have better overall aerodynamic performance over the rigid wing, especially for low speed applications. The wood (rigid) wing exhibited better lift production performance in quasi steady regime.
Effects of Aircraft Tail Configurations on Sensitivity to Yaw Disturbances
Authors: Musa Nur Amalina , Mansor S. , Ali Airi , Wan Omar Wan Zaidi , Abdul Latif Ainullotfi , Perumal Kannan
Published: October 2014

A wind tunnel test was conducted to compare the characteristics of low speed stability and control for aircraft with conventional tail and V-tail configurations. Comparison was made in terms of static directional stability at selected test speed of 40 m/s, which corresponds to Reynolds number of 0.1622 x 106 based on the chord. Three types of simplified tail-only model were tested in Universiti Teknologi Malaysia's Low Speed Wind Tunnel (UTM-LST). Results show that the V-tail configuration greatly affects the aerodynamic characteristics in directional stability as the side force and yaw moment tends to vary linearly with yaw angles up to 25 degrees, compared to conventional tail that has linear characteristics up to only 10 degrees yaw
Synthesis of Optimal Distributed Measurement Systems for Control of an Elastic Object
Authors: Panferov Аlexander , Nebylov Alexander , Brodsky Sergey
Published: October 2014

Effective control of an elastic space vehicle is possible only on the basis of exact information on its elastic oscillations. Exact estimation of these oscillations is possible via a distributed system of measuring instruments installed in different points of the elastic design. In recent years, new types of inertial measuring devices came into use like micro-electro-mechanical (MEMS) gyroscopes and accelerometers. Significant progress in the development of on-board computers allows the use of modern means of filtering algorithms, based on numerical integration of a large number of differential equations in real time. Miniaturization of sensors and the decrease of their power consumption increases admissible quantity of used sensitive elements and reduces restrictions for their placement. This article presents new results on optimization of placement of system of sensors on an elastic controlled object.
Comparison of Auxiliary Power Unit (APU) and Ground Power Unit (GPU) with Life Cycle Analysis in Ground Operations: A Case Study for Domestic Flight in Turkey
Authors: Altuntas Onder , Selcuk Ekici , Yalin Gorkem , Karakoc T. Hikmet
Published: October 2014

In this study, the Auxiliary Power Unit (APU) and the Ground Power Unit (GPU) that are required meet the energy demand in ground operations of aircraft were compared in terms of their damages –human health (disability adjusted life years- DALYs), ecosystem quality (PDF.m2.yr) and resources (MJ Surplus). These damages were calculated with gate-to-gate method of Life Cycle Assessment (LCA). This assessment was held on three main stages; capital investment, operation and maintenance. SimaPro 7.2.4 was used for this calculation. Human Health Damages (HHDs) of APU were found to be (0.0557 -disability adjusted life years- DALYs) 20.34 days/year while HHDs of GPU were calculated as (0.0411 -disability adjusted life years-DALYs) 15 days/year. While Ecosystem Quality Damages (EQDs) of APU were calculated as 103366.37 PDF.m2.yr, EQDs of GPU were found to be 82651.23 PDF.m2.yr. In other words, although the use of APU gives rise to loss of 0.1 species –1 year, 1 square kilometer area, the use of GPU gives rise to loss of 0.083 species. With regards to Resources Damages (RDs), 62125 MJ surplus energy needed for future extractions of minerals and fossil fuel considering APU, one the other hand 36002 MJ surplus energy needed for future considering GPU. As a result, the use of APU effects on human health, ecosystem quality and resources was determined greater than the use of GPU for 30 minute. The use of GPU has less impact on human health, ecosystem quality and resources in ground operations.
Data Filter Performance for Rocket Thrust Measurement System
Authors: Abdullah Nor Hafizah , Wahida Ku Chik Tengku Farah , Zaraini Fairul Azmin
Published: October 2014

This research focuses on the electrical noise coming from the sensor: load cell which is being used in rocket thrust measurement system. The aim is to investigate the noise contained in the measurement data. Fast Fourier Transform (FFT) is used as an indicator for appropriate cut off frequency in filtering data. Low Pass Filter is used as the measurement of thrust for it produces steady-state signal and acceptable transient response. Results confirmed that there are significant differences for Signal Noise Ratio (SNR) value between filtered and unfiltered data. Data noise has an impact to the true value of the expected results that affects data interpretation. It is shown that the influence of noise on the measurement data has been successfully reduced by the method used.
Quadrotor UAV Indoor Localization Using Embedded Stereo Camera
Authors: Azrad Syaril , Fadhil Mohammad , Kendoul Farid , Nonami Kenzo
Published: October 2014

Localization of Small-Size Unmanned Air Vehicles (UAVs) such as the Quadrotors inGlobal Positioning System (GPS)-denied environment such as indoors has been done using varioustechniques. Most of the experiment indoors that requires localization of UAVs, used cameras or ultrasonicsensors installed indoor or applied indoor environment modification such as patching (InfraRed) IR and visual markers. While these systems have high accuracy for the UAV localization, theyare expensive and have less practicality in real situations. We propose a system consisting of a stereocamera embedded on a quadrotor UAV for indoor localization. The optical flow data from the stereocamera then are fused with attitude and acceleration data from our sensors to get better estimationof the quadrotor location. Using stereo camera capabilities the quadrotor altitude are estimated usingSIFT Feature Stereo Matching are used in addition to the altitude estimation computed using opticalflow. To avoid latency due to computational time, image processing and the quadrotor control areprocessed threads and core allocation.
Tether Tension Performance Utilizing Various Materials for a Coplanar and Non-Coplanar Model of a Flexible Tethered Satellite System
Authors: Hong Aaron Aw Teik , Varatharajoo Renuganth
Published: October 2014

This paper presents a numerical model for a flexible tethered satellite system in both planar and co-planar environment. This tethered satellite system consists of three rigid bodies with two flexible tethers, each connecting two rigid bodies with one located in the center serving as the mothership. The dynamics of the system include tether deformations, rotational dynamics and orbital mechanics. Five different materials that are commonly used will be tested accordingly in order to observe its performance based on the tension of the tether. It is found that, based on all of the materials simulated, diamond has the best tension performance.
Three-Axis Attitude Control Performance of a Small Satellite Using Control Moment Gyroscope
Authors: Salleh Mohd Badrul , Suhadis Nurulasikin Mohd
Published: October 2014

In this paper, a three-axis attitude control of a small satellite employing control moment gyroscope (CMG) is presented. A four single gimbal control moment gyroscopes (4-SGCMG) cluster has been employed as the actuator and a proportional-derivative (PD) based attitude control approach has been utilized. The singularity robust (SR) steering law has been employed to investigate its capability in avoiding the singularity state of the CMG system with respect to the mission operation by setting the initial gimbal angle further from the singularity state. The presented control law was simulated in the MATLAB® SIMULINK® software. Results obtained from the simulation show the effectiveness of the control algorithm.
Numerical Simulation of Noise Radiated from a Blunt Trailing Edge
Authors: Mohd Haris Siti Nur Aishah , Mat Ali Mohamed Sukri , Shaikh Salim Sheikh Ahmad Zaki , Muhamad Sallehuddin , Mahzan Muhammad Iyas
Published: October 2014

The Lighthill acoustic analogy is applied to estimate the noise radiation from ﬂow over a blunt trailing edge. The blunt trailing edge is an effective vortex generator. Periodic vortex shedding near the trailing edge induces ﬂuctuating lift that radiates a strong Aeolian tone. The frequency of the Aeolian tone is similar to that of the vortex shedding. A 50.1 dB of Aeolian tone level is radiated from this blunt trailing edge.
Flight Management System for Unmanned Reusable Space Vehicle Atmospheric and Re-Entry Trajectory Optimisation
Authors: Ramasamy Subramanian , Sangam Manoj , Sabatini Roberto , Gardi Alessandro
Published: October 2014

The design and trajectory computation algorithms of an innovative Flight Management System (FMS) for Unmanned Reusable Space Vehicle (URSV) are presented. The proposed FMS features a number of common functionalities with modern aircraft FMS that enable flight planning in non-segregated airspace, as well as specific features for optimal trajectory generation and space segment monitoring of the flight mission. The general avionics architecture of URSV is presented and the specific FMS algorithms are developed to cope with the flight vehicle optimal trajectory planning and monitoring. Simulation case studies are performed in a realistic operational scenario resulting in the rapid generation of feasible trajectories, ensuring no violation of the defined mission and vehicle dynamics constraints. Additionally, error budget analysis is performed on longitudinal profile trajectories to evaluate the URSV performance.
Sliding Mode Control Techniques for Combined Energy and Attitude Control System
Authors: Eshghi Samira , Varatharajoo Renuganth
Published: October 2014

Combined Energy and Attitude Control System (CEACS) is an optimization approach that combines the energy storage system and the attitude control system. With a double counter rotating flywheel simultaneously serving as energy storage device and as attitude control actuator, CEACS requires an accurate control strategy to obtain the mission requirements. In addition, it is important to design the control law to be invariant to uncertainties and disturbances, and guarantee robustness as CEACS inherits these in-orbit uncertainties. This paper presents a nonlinear control employing sliding mode to enhance the CEACS attitude control capability. The mathematical model for the conventional and boundary layer sliding mode controls are developed herein for CEACS. The controller provides enhancement in pointing accuracies, reasonable transient responses and a robustness against uncertainties and in-orbit disturbances.
Basic Geometries of the New Closed Circuit Wind Tunnel of the Universiti Putra Malaysia (UPM)
Authors: Wiriadidjaja Surjatin , Mohd Rafie Azmin Shakrine , Mustapha Faizal , Hasim Fadilah , Khan Tabrej , Djojodihardjo Harijono
Published: October 2014

The existing UPM low speed wind tunnel was usually occupied by students, who carried out their final year projects or postgraduate researches, so that there was hardly free time slot for any additional testing work. Due to this reason, a new wind tunnel project has been started recently. Some basic specifications of the new tunnel have been pre-selected before the project was started, which comprised the following design decisions: a tunnel speed of 50 m/s, a test section area of 1´1 m2, and a closed circuit tunnel type. It wouldn’t be difficult to perceive that this pre-selection was made based on some of the trade-off results among the project’s options and constraints. This paper is aimed to present a simple analysis on the design of the new tunnel, focusing only on its basic geometries. Some design decisions that have been made related to its basic geometries are analyzed and reported in this paper. This analysis may be considered as a design verification of the new tunnel or even perhaps be regarded as scientific justification for its existence.
Computational Analysis of the Groove Effect to Reduce the Cavitation in Ball Valves
Authors: Yusof N.S.B. , Mohd Rafie Azmin Shakrine , Ariffin M.K.A. , Othman N.
Published: October 2014

Cavitation is a phenomenon that frequently creates fear within the engineering industry as the violent and critical attacks by cavitation can cause a lot of damage to ball valves. This paper is presented to reduce the risk of cavitation attack due to dramatic pressure drop and to demonstrate the ball valve performance. The ball valve with grooves was simulated and compared with current method under same boundary conditions as with existing experimental of ball valves. The proposed device can be operated in aircraft to isolate the fuel system and the engine fuel system after engine shutdown or emergency. The proposed implementation has successfully shown to eliminate the dramatic pressure drop effects to the ball valve. In the case study, at a closing angle of 40° at which violent cavitation occurs, the ball valve showed increasing cavitation intensity performance to 0.3 or 30%. The average performance of the cavitation index for all cases also increased to 24%.
Effect of Short Time Sintering on the Mechanical Properties of Undoped Zirconia Ceramics
Authors: Sivakumar Sivanesan , Singh Ramesh , Teow Hsien Loong , Chuan Yong Leng , Leong Jeffrey Kong Chin
Published: October 2014

Sintering parameters are undoubtedly among the many factors that influence the mechanical properties and hydrothermal ageing resistance of tetragonal zirconia ceramics. In this research, the effect of using short holding times i.e. (1 min., 30 min. and 1 hour) as compared to the conventional 2 hours during sintering of 3 mol% Yttria Tetragonal Zirconia Polycrystals (3Y-TZP) on the mechanical properties were systematically investigated. The research revealed that holding time of 1 minute and sintered at 1400oC yielded a high relative density (above 95% of theoretical density) and high Young’s modulus (above 180 GPa) without compromising on tetragonal phase stability and mechanical properties. The study also revealed that the bulk density is an important parameter governing the matrix stiffness of 3Y-TZPs and that grain size strongly influences the transformability and consequently, the toughness of 3Y-TZPs. The toughness of the ceramic was observed to increase steeply when grains exceeded 0.52 µm, which has been identified as the critical grain size for toughening.
Development of a Wind Tunnel DAQ Using LabVIEW Tools
Authors: Rodríguez-Sevillano Angel Antonio , Barcala-Montejano M.A. , Sacristán-Callejo S.
Published: October 2014

This paper presents the experimental three-year learning activity developed by a group of teachers in a wind tunnel facility. The authors, leading a team of students, carried out a project consisting of the design, assembly and testing of a wind tunnel. The project included all stages of the process from its initial specifications to its final quality flow assessments, going through the calculation of each element, and the building of the whole wind tunnel. The group of (final year) students was responsible for the whole wind tunnel project as a part of their bachelor degree project. The paper focuses on the development of wind tunnel data acquisition software. This automatic tool is essential to improve the automation of the data acquisition of the wind tunnel facility systems, in particular for a 6 DOF multi-axis force/torque sensor. This work can be considered as a typical example of real engineering practice: a set of specifications that has to be modified due to the constraints imposed throughout the project, in order to obtain the final result.
Sensing Unsteady Pressure on MAV Wings: A New Method for Turbulence Alleviation
Authors: Marino Matthew James , Watkins Simon , Sabatini Roberto , Gardi Alessandro
Published: October 2014

Experiments at low Reynolds numbers were performed on a pressure tapped NACA 2313 wing in a 3 x 2 x 9 meter wind tunnel under nominally smooth (Ti = 1.2%) and turbulent (Ti = 7.2%) flows at a mean flow velocity of 8ms-1(Re ≈120,000). The NACA 2313 wing is a replica of Micro Air Vehicle (MAV) wing of the Flash 3D aircraft used at RMIT University for research purposes. Unsteady surface pressures were measured to understand if the information could be adopted for resolving turbulence-induced perturbations and to furthermore use it in a turbulence mitigation system. Two span-wise locations of chord-wise pressure were acquired when tested under the two different flow conditions. It was discovered that at both span-wise locations, a local Coefficient of Pressure (Cp) held high correlation to the chord-wise Cp integration and allowed for a linear relationship to be formed between the two variables. The defined relationship provided a 95% confidence for angles of attack below stall and was used to estimate the integrated chord-wise pressure coefficient at a particular span wise location. The relationship between a single pressure tap and the integrated Cp of that chord-wise section was valid for the two different span-wise locations with similar defining equations. As one pressure tap is sufficient to adequately estimate the integrated Cp on a chord-wise wing section, a limited amount of pressure taps across the wings span approximates the pressure distribution across the span and eventually approximates the flight perturbations. Being a novel method of sensing aircraft disturbance, applications are not restricted to MAV. The methodology presented could very well be applied to larger aircraft to reduce the effects of turbulence within the terminal area and can provide other means of active stabilization.