bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of the Thermo-Fluids of Gearbox Systems
Authors:   United Technologies Research Center, Yazdani Miad , Soteriou Marios , Chaudhry Zaffir , Sun Fanping
Published: October 2024

Gearboxes are fundamental to the operation of a helicopter. For instance, the two-stage planetary gearbox system converts the high-speed, low-torque output of one or more engines and delivers it to a high-torque, low speed rotor. The thermal and multiphase flow physics are among the leading determinants of the performance, durability and life of these systems and are crucial to devising optimization guidelines to minimize the power loss associated with the operation of the gearbox. For instance, the thermal state, i.e. temperatures of gears, bearing and lubricant are critical parameters affecting the life and performance of these components. In addition, the local oil flow distribution in the vicinity of the gears meshing region along with its temperature-dependent properties are amongst the primary variables controlling the liquid film thickness, hence the contact-generated heat. Despite the significance of the thermo-fluids of the gearbox system, however, limited capability has been developed to predict and characterize these phenomena in a wholistic fashion. This is, in part, due to the significant complexity and multi-scale nature of the physical phenomena involved. This paper demonstrates the application of a recently developed modeling methodology (Ref. 1) for predicting the time-dependent thermo-fluid state of the gearbox system on a set of three interlocking gears that serve as a validation vehicle. Along with the modeling approach which is applicable to any multiscale problem of this nature, a novel gridding methodology is presented for simulating interlocking gears with substantially improved accuracy. The long-term (time-independent) temperature distribution within the gearbox is obtained through the proposed simulation method and compared to the experimental measurements. In addition, the model is shown to be able to reproduce the temporally cyclic temperature oscillations once the system reaches the stationary-state condition.
Analysis of Impact Behavior of Thick Rotorcraft Composite Components: Approach and Implementation
Authors:   Sikorsky Aircraft Corporation, Bouquillon Brian ,   United Technologies Research Center, Gurvich Mark , Davis Mark , Rao Prabhakar , Clavette Patrick
Published: October 2024

The Sikorsky Aircraft Corporation (SAC) and the U.S. Army Aviation Development Directorate-Aviation Applied Technology Directorate (ADD-AATD) are jointly sponsoring the Capability-Based Operations and Sustainment Technology-Aviation (COST-A) program. The objective of COST-A is to demonstrate an integrated set of high-value diagnostics, prognostics, and system health management technologies that reduce the maintenance burden, without sacrificing safety, of six different rotorcraft systems, including the rotor impact detection and damage assessment. Impact damage behavior of large rotorcraft composite structures (RCS) is a complex problem and a challenging application for development of efficient and reliable predictive models. Thus, the objective of this work is a) development of a general approach of impact damage assessment, specifically for thick RCS; and b) demonstration of the approach on representative test articles. The approach is primarily based on multi-scale definition of RCS and test/model integration to understand and validate the most relevant damage mechanisms. Cohesive-element based FEA is applied for computational implementation of the approach. The approach was demonstrated on a main rotor blade (MRB) composite spar subjected to impact events. Representative examples that were investigated indicate the robust nature of the developed capabilities to capture multiple interlaminar damage patterns. Computational convergence is demonstrated for a range of load scenarios and damage mechanisms. Developed predictive capabilities can be used for systematic parametric studies to either define the worst case scenario for impact damage assessment or potential optimization of the internal structure in design to reduce susceptibility. It also may potentially help to reduce cost of full-scale testing and accelerate the entire certification process of RCS.
Managing Certification for Software and AEH on Military Programs
Authors:   The Boeing Company, Lenahan Susan
Published: October 2024

The requirement for airworthiness certification on military programs has created an increased demand for programs to include adherence to RTCA/DO-178B for Software Development and RTCA/DO-254 for Airborne Electronic Hardware (AEH) Development. The demands of ensuring detailed process control and rigorous development of products in compliance to these standards is a recent addition to the military industry's technical culture. Configuration Status Accounting can be employed by Systems Engineering in managing avionics systems development to RTCA/DO-178B and RTCA/DO-254. Presenting the practices employed by the Chinook Systems Engineering Certification team will provide insight into using predictive tools and processes that have saved time, provided consistency in reporting, and increased customer satisfaction and understanding of performance across systems within multiple international programs. Reference to DO-178 will refer to the use of either DO-178 or to DO-254 standards as the strategy and techniques discussed to manage compliance activities are consistent for both standards' guidance.
A Dynamic View for Exercising Functions for Integrated Product and Process Development
Authors:   Georgia Institute of Technology, Schrage Daniel
Published: October 2024

Systems Engineering approaches, such as the use of the Vee Diagram, illustrate static product and process approaches, but don't explicitly display the roles that Product Development Cycle Time (PDCT) and Product Lifecycle Management (PLM) play in exercising Integrated Product and Process Development (IPPD). A generic IPPD methodology has been developed at Georgia Tech for exercising integrated product and process trades, utilizing the interaction of four key elements: Systems Engineering methods, Quality Engineering methods, a Top Down Design Decision Support process and a Computer Integrated Environment. However, a dynamic view of how these methods and tools interact is needed. Recently, the Georgia Tech Integrated Product Lifecycle Engineering (IPLE) Laboratory has developed this dynamic view and applied it for Advancing Informal STEM Learning (AISL). This has been accomplished over the past few years through Team-based Engineering And Manufacturing (TEAM) high school summer camps. This paper presents the results from the TEAM high school summer camps and how it is now being applied in other applications for expanding STEM student lifelong learning.
Three-dimensional Reconstruction of Blade Tip Vortices of a BO 105 using a Multi-camera BOS System
Authors:   German Aerospace Center (DLR), Bauknecht Andre ,   French-German Research Institute of Saint Louis, Leopold Friedrich , Ewers Benjamin , Wolf Christian , Raffel Markus
Published: October 2024

Noise and structural vibrations in rotorcraft are strongly influenced by interactions between blade tip vortices and the structural components of a helicopter. As a result, the three-dimensional localization of vortices is highly desirable, especially for the case of full-scale helicopters under realistic flight conditions. In the current study, we present results from a flight test with a full-scale BO 105 in an open pit mine. A background-oriented schlieren measurement system consisting of ten cameras was used with a natural background to visualize the vortices of the helicopter under maneuvering flight. Vortex filaments could be visualized and extracted up to a vortex age of 360°. Vortex instability effects were found for several flight conditions. Due to the large test dimensions, an iterative approach based on points on the helicopter fuselage was applied for the camera calibration. Point correspondence between vortex curves in the evaluated images was established by means of epipolar geometry. A three-dimensional reconstruction of the main part of the vortex system was carried out for the first time using triangulation-based stereo-photogrammetry. A quantitative evaluation of the 3D vortex system was carried out, demonstrating the potential of the multi-camera background-oriented schlieren measurement technique for the analysis of blade-vortex interaction effects in rotorcraft.
Design, Development, and Hover Testing of a Helicopter Rotor Blade Chord Extension Morphing System
Authors:   US Naval Air Systems Command, Hayden Eric ,   Rensselaer Polytechnic Institute, Gandhi Farhan
Published: October 2024

A rotor blade chord extension system was designed, fabricated and hover tested, using electromechanical and pneumatic actuation. A 1.5 in actuator stroke output in the spanwise direction was converted into chordwise motion of a trailing-edge plate, via a rigid link. On the hover stand, with a 20 Volt DC input, the electromechanical actuator was shown to fully extend and retract the plate at rotational speeds up to 385 RPM (which put the system at a centrifugal loading of 209.5 g, or 47.2% of that on a Black Hawk helicopter at 73% span). The configuration was changed to reduce the actuator force requirement for the pneumatic actuator. The rotor test facility allowed a maximum of 105 psi pressure input through the rotary union (significantly lower than the rating of the actuator). At these moderate pressure inputs, full trailing-edge plate deployment was observed at 315 RPM (140.2 g, or 31.6% of that on a Black Hawk helicopter at 73% span). The model prediction of trailing-edge plate displacement versus pressure showed good correlation with test results.
First NICETRIP Powered Wind Tunnel Tests Successfully Completed in DNW-LLF
Authors:   Agusta, Stabellini Alessandro ,   DNW - German-Dutch Wind Tunnels, Philipsen Iwan ,   National Aerospace Laboratory - NLR, Hakkaart Joost ,   DLR, Langer Juergen , Verna Alberto , de Anton , Schneider Oliver , Przybilla Michael
Published: October 2024

A team of European Industry and academic researchers led by AgustaWestland, a Finmeccanica company, have successfully completed wind tunnel tests of a 1/5th scale model of a tiltwing/tiltrotor aircraft called ERICA (Enhanced Rotorcraft Innovative Concept Achievement) at the DNW-LLF wind tunnel (German-Dutch Wind Tunnels Large Low-speed Facility) in July 2013. This intensive research is partially funded by the European Commission under an EU sixth framework programme called NICETRIP (Novel Innovative Competitive Effective Tilt Rotor Integrated Project). As part of the NICETRIP programme, a 1/5th scale full-span, powered wind tunnel model was designed by NLR, and then manufactured in Russia and The Netherlands. Before entering the wind tunnel on June 18, 2013, extensive instrumentation calibrations, ground vibration tests, tracking & balancing and pre-tests were conducted in the exp. hall of DLR Inst. of flight systems Braunschweig and at DNW-LLF. Once inside the wind tunnel, seven trimmed conditions, representing hovering, transitioning and airplane mode, were tested. For each of these trimmed conditions a comprehensive number of variations (incidence, sideslip, nacelles, tilting outboard wings angles, flaps, flaperons, rudder and elevator angles, blade collective pitch angles...etc) were performed; resulting in a total of over 400 different flight conditions including an exploration towards the boundary of the conversion corridor. For each of the 400 flight conditions, over 800 parameters were recorded; consisting of about 50 parameters from balances loads, strain gages and accelerometers measurements, flight controls position, power required, over 700 static and dynamic pressures channels and a range of safety monitoring parameters. Due to the complexity of the model and numerous aircraft design variables, testing was extremely complex and challenging, during which many minor issues were discovered, but quickly resolved by the team. The test was successfully completed on schedule on July 5th, thanks to the skill and experience of the integrated AgustaWestland, DNW, DLR and NLR team involved in the testing.
Icing Wind Tunnel Test of a Full Scale Heated Tail Rotor Model
Authors:   Bell Helicopter, Wright Jason , Aubert Roger
Published: October 2024

In August and September of 2013 a rotor blade icing test was conducted at NASA Glenn Research Center's Icing Research Tunnel (IRT). The test model was a two bladed, teetering rotor with electro-thermal heater blankets installed onto the blades. The model was developed as part of the Vertical Lift Consortium (VLC) project entitled, "High Fidelity Icing Analysis for Rotors". This project was a collaborative effort between industry, academia, and government. This paper will present a description of the motivation behind the test, the model design, and the installation. This paper will also present a summary of the configurations, conditions, and challenges encountered during testing.
Performance and Flowfield Measurements of a Micro-Air-Vehicle Scale Helicopter Rotor
Authors:   University of Maryland, Winslow Justin , Hasnain Zohaib , Benedict Moble , Chopra Inderjit
Published: October 2024

This paper describes the systematic performance measurements and flowfield studies (PIV) conducted towards understanding and optimizing the hover performance of a MAV-scale helicopter rotor operating at Reynolds numbers of 30,000 or less. The rotor parameters that were varied include blade airfoil profile, blade chord, number of blades, blade twist, planform taper and winglets at blade tip. Blade airfoil section had a significant impact on the hover efficiency and among the large number of airfoil sections tested, the ones with the lower thickness to chord ratios and moderate camber (4.5% to 6.5%) produced the highest rotor hover figure of merit. Increasing the solidity of the rotor by increasing the number blades (constant blade chord) had minimal effect on efficiency; whereas, increasing the solidity by increasing blade chord for a 2-bladed rotor, significantly improved hover efficiency. Moderate blade twist (-10° to -20° ) and large planform taper (larger than 0.5) marginally improved rotor efficiency. Rotor blades with small winglets (height ≈ 6% of rotor radius) at the tip also improved hover performance. Using winglets, the flowfield measurements showed a diffused tip vortex, which could reduce the induced aerodynamic losses. Spanwise lift distribution obtained using sectional bound circulation computed from the measured flowfield correlated well with the load cell measurements. The optimal rotor designed based on the understanding gained from the present study produced a figure of merit of 0.67, which is the highest value of FM ever reported in the literature for micro-rotors operating at these low Reynolds numbers.
Experimental Characterization of a Small-Scale Tailboom with Fluidic Flexible Matrix Composite Tubes
Authors:   Pennsylvania State University, Miura Kentaro ,   Bell Helicopter, Romano Peter , Krott Matthew , Smith Edward , Rahn Christopher
Published: October 2024

Rotorcraft tailbooms vibrate due to excitation from the rotors, separated flow behind the rotor hub, vehicle maneuvers, and wind gusts. They also typically have low inherent structural damping. This vibration leads to driveline component wear, structural fatigue, and passenger discomfort. Fluidic Flexible Matrix Composite (F2MC) tubes, a new class of passive vibration treatments, are attached to a representative tailboom structure and experimentally tested. Each F2MC tube consists of a stainless steel mesh surrounding a rubber tube. The mesh and tube are independently fastened to end fittings that mechanically connect and fluidically seal the F2MC tubes, respectively. Two tubes are mounted to the top and bottom of the tailboom and interconnected with a fluidic circuit that can be pressurized. Tests are performed to measure the fluid volume pumped by the F2MC tubes when the tailboom bends, and the tailboom displacement in response to F2MC tube pressurization. Experimental results demonstrate that the F2MC tubes can actuate tailboom bending and pump fluid. The actuation and fluid pumping results agree well with theoretical predictions. Numerical simulations, based on a previously developed model, have indicated potential for F2MC tubes to provide an efficient means of introducing useful levels of damping into tailboom structures. Characterization of the dynamic performance is ongoing.
Performance and Vibratory Hub Loads of a Mach-Scale Coaxial Rotor in Hover
Authors:   University of Texas Austin, Cameron Christopher , Karpatne Anand , Sirohi Jayant
Published: October 2024

A Mach-scale, rigid, counter-rotating coaxial rotor system, 80 inches in diameter and operating at tips speeds up to 625 feet per second, was built and hover tested in three configurations: two-bladed single rotor, four-bladed single rotor and two-bladed counter-rotating coaxial rotor. The blades were untwisted with a VR-12 airfoil profile and a constant chord of 3 inches with a 0.15 inch trailing-edge tab. The rotors were tested up to a maximum blade loading (CT/μ) of approximately 0.095. Dynamic hub load data, as well as lower rotor pushrod loads were recorded with synchronous averaging implemented using a main rotor shaft 1/rev trigger. Mean loads were used to analyze rotor performance, as well as to validate an in-house, free vortex wake model (FVM). The performance of the coaxial configuration was found to be indistinguishable from that of a four-bladed single rotor of equal solidity and planform while individual upper and lower rotor performance was degraded compared to a two-bladed single rotor. The FVM was shown to accurately capture both total system loads, as well as trends in upper and lower rotor thrust sharing. Preliminary results for vibratory thrust loads indicated larger coaxial rotor vibratory loads at several n/rev harmonics compared to an isolated single rotor. The azimuthal variation of lower rotor thrust, compared with that of an isolated single rotor, revealed evidence of aerodynamic interaction with passing upper rotor blades.
Comparative Bench Test Assessment of Medium Authority On-blade Actuation Technologies
Authors:   InnoVital Systems Inc., Kothera Curt ,   Invercon LLC, Szefi Joe ,   Bell Helicopter, Schank Troy
Published: October 2024

Trailing Edge (TE) servo flaps embedded in the outer portion of a rotor blade have been proposed for both primary flight control and higher harmonic controls. The flight control application requires large 1/rev flap displacements on the order of ±15°. Higher harmonic control applications require less flap displacement, but greater bandwidth. Higher harmonic active control of vibration and acoustics can generally be achieved with small flap deflections of approximately ±1° or less. However, rotor power reduction appears to benefit from medium deflections, on the order of +5° to +10° at 2/rev through N+1/rev frequency content. Research at Bell Helicopter has been conducted to explore actuation methods that are capable of medium flap deflections up to N+1/rev frequencies to enable performance improvements, in addition to vibration and noise benefits. Three medium authority on-blade actuation approaches are developed against a common set of requirements generated for a Bell model 430 rotor blade with a TE flap. Actuator technologies investigated include one electromagnetic and two flexible membrane pneumatic actuator configurations, including a pneumatic muscle and pneumatic diaphragm. Each actuator is fabricated and bench tested against a common set of conditions to provide a side-by-side comparison of key performance metrics and to gain practical experience. Test results indicate that all three actuation approaches have sufficient stroke, torque and bandwidth potential for the medium authority on-blade application. The electromagnetic linear motor and drive mechanism approach is mechanically complex and heavy relative to the pneumatic approaches. The pneumatic muscle approach is light and compact, but its linear output requires additional mechanisms to connect to the flap and remain within the blade contour. The pneumatic diaphragm approach is powerful and compact, and connects to the flap in a mechanically simple way, with the lowest installed mass of the three configurations. Both flexible membrane pneumatic actuators have great promise for the medium authority on-blade actuation application.
OH-58 Block II Control Law Upgrades
Authors:   Bell Helicopter, Shue Shyhpyng , Carlson Eric , Schillings John , Bothwell Mike
Published: October 2024

The Bell Helicopter OH-58 Block II Concept Demonstrator was developed under an internal research and development program. In 2011, the Block II aircraft demonstrated HOGE Performance at 6000 ft pressure altitude, 95 degrees Fahrenheit (6k95F), for test conditions that exceeded the maximum gross weight. As part of the overall development program, the OH-58D baseline control laws were updated to improve handling qualities. This paper describes the control law changes and the resulting improved handling qualities. VMS studies were initiated to assess the main rotor cyclic actuator arrangement. CIFER and COPTER linear aircraft models were developed to support the analysis in conjunction with the CONDUIT flight control design tool. Ultimately, Level 1 Handling Qualities were achieved in the demonstrator aircraft. Predicted optimal SCAS gains were tuned during flight tests. ADS-33 MTE maneuvers were evaluated by both Bell and Army flight test pilots. Pilots were very impressed by the improved handling qualities achieved through this process, making the OH-58 Block II Demonstrator a great candidate for a potential future light scout/attack helicopter.
Full-scale Experimental Validation of Dynamic, Centrifugally Powered, Pneumatic Actuators for Active Rotor Blade Surfaces
Authors:   Kaman Aerospace Corporation, Cormier Brian ,   Invercon LLC, Szefi Joseph , Ionno Luke
Published: October 2024

A novel actuation approach for active rotor blade surfaces is introduced. The approach utilizes the rotor centripetal acceleration to generate an internal, on-blade pressure differential that can be used for active surface actuation. The advantages of this approach include high force and displacement output with extremely little added blade weight and low electrical power requirements. An analysis of the available spanwise pressure differential is presented that has been previously experimentally validated in a full-scale whirl test of a K-MAX rotor. The development of a scaled pneumatic actuator designed to fit within a K-MAX rotor blade is then detailed. The actuator consists of miniature, three-way piezoelectric valves that control air flow into and out of actuating diaphragms. The experimental results of a full-scale whirl test are then reported. The rotational actuator is capable of following various multi-frequency command signals with frequency components up to 30 Hz, and the results suggest that actuator performance and response time could be improved with increased valve flow. A state space model of a pneumatic actuator and trailing edge flap system is then developed that captures the instantaneous air flow through the valves into the diaphragms, as well as the flap dynamics. Upon model validation using the experimental whirl test results, an analytical feasibility study is then conducted to determine the valve and diaphragm geometry requirements to power a trailing edge for both higher harmonic vibration control and primary flight control for a light-medium sized helicopter. This study assumes that the actuator must provide at least ±5° at 30 Hz for vibration control and ±20° at 6 Hz for primary control. The results of this study suggest that the actuation approach can provide sufficient torque and angular displacement at the required bandwidths provided there is adequate valve performance and a minimum pneumatic supply line diameter. Using the Darcy-Weisbach formula for flow through pipes, a minimum diameter for the supply line diameter to maintain a sufficient pressure differential is estimated given the volumetric air flow through the actuator. The effects of forward flight and varying altitude on the available pressure differential is investigated, where the azimuthal RMS pressure differential is little changed in forward flight versus hover and the available pressure differential decreases nearly in proportion to the decreasing air density with altitude. Because aerodynamic forces on active surfaces also decrease in proportion to air density, a pneumatic actuator can therefore be designed to be operable in all flight regimes. Finally, a next generation actuator design is presented that will enable high frequency, high displacement actuator performance.
The Planner Ensemble and Trajectory Executive: A High Performance Motion Planning System with Guaranteed Safety
Authors:   Carnegie Mellon University, Scherer Sebastian , Choudhury Sanjiban , Arora Sankalp
Published: October 2024

Autonomous helicopters are required to fly at a wide range of speed close to ground and eventually land in an unprepared cluttered area. Existing planning systems for unmanned rotorcrafts are capable of flying in unmapped environments, however they are restricted to a specific operating regime dictated by the underlying planning algorithm. We address the problem of planning a trajectory that is computed in real time, respects the dynamics of the helicopter, and keeps the vehicle safe in an unmapped environment with a finite horizon sensor. We have developed a planning system that is capable of doing this by running competing planners in parallel. This paper presents a planning architecture that consists of a trajectory executive - a low latency, verifiable component - that selects plans from a planner ensemble and ensures safety by maintaining emergency maneuvers. Here we report results with an autonomous helicopter that flies missions several kilometers long through unmapped terrain at speeds of upto 56 m/s and landing in clutter. In over 6 months of flight testing, the system has avoided unmapped mountains, popup no fly zones, and has come into land while avoiding trees and buildings in a cluttered landing zone. We also present results from simulation where the same system is flown in challenging obstacle regions - in all cases the system always remains safe and accomplishes the mission. As a result, the system showcases the ability to have a high performance in all environments while guaranteeing safety.
A Real Time Expert Control System for Helicopter Autorotation
Authors:   Georgia Institute of Technology, Rogers Jonathan ,   Texas A&M University, Sunberg Zachary , Miller Nate
Published: October 2024

A control algorithm for autonomous helicopter autorotation is proposed and evaluated. The algorithm consists of a multi-phase control law with fuzzily-defined transitions, and provides outputs in the form of collective commands, desired forward speed, and maximum pitch and roll angle limits. The algorithm is designed to be used in conjunction with an inner loop velocity tracking controller. A unique feature of the proposed control law is its use of estimated time to ground impact to compute near-optimal flare trajectories from a wide range of initial conditions. Performance of the proposed expert control system is evaluated through six-degree-of-freedom simulation of both a full-size helicopter and a small hobby-size helicopter, and Monte Carlo examples demonstrate robustness to various initial flight conditions. Limited flight test results are presented demonstrating suitable performance of the algorithm in realistic disturbance environments.
Gurney Flap Control Authority on a Pitching Wind Turbine Airfoil
Authors:   University of Wyoming, Naughton Jonathan , Nikoueeyan Pourya , Strike John , Hind Michael , Magstadt Andrew
Published: October 2024

Rotation of the wind turbine blade through the atmospheric shear layer imposes highly unsteady aerodynamic conditions over the blade resulting in stall, unwanted oscillatory loads, and accompanying deflections. In this study, the effectiveness of the Gurney flap in static and dynamic stall regimes has been evaluated for possible flow control applications. The effect of flap height on the lift and moment coefficients has been investigated using time-resolved pressure measurements at a Reynolds number (Re) of 430,000. In addition, velocity field measurements were made using Particle Image Velocimetry (PIV) to further investigate the changes in the physical mechanisms that occur when the flap is deployed. Static results show a significant change in section lift and moment coefficients comparable with conventional flaps. The behavior of the blade in the dynamic stall regime is also highly affected by the presence of the Gurney flap. When the Gurney flap is on the pressure side of the airfoil, lift coefficients increase in all flow regimes. Deployment of the flap on the suction side can still affect the flow in moderate stall conditions even under post stall conditions, although in the deep stall regime the effects are limited.
The message of our generations to the new generations
Authors: Antico Leonardo
Published: October 2024

Not available.
The rules on gender reassignment and the problem of transsexualism
Authors: Bompiani Adriano
Published: October 2024

Not available.
Health and Christian salvation in the context of health education
Authors: Sgreccia Elio
Published: October 2024

Not available.
The debate on artificial insemination in medical-moral reflection in Italy over the last decade
Authors: Leuzzi Lorenzo
Published: October 2024

Talking today about artificial insemination certainly no longer arouses wonder. Man's lordship over creation, in fact, registers a singular breadth with unprecedented and surprising results, especially in the field of the physio-pathology of reproduction: intrauterine diagnosis of genetic diseases, control or even sex determination, the most diverse genetic experiments for therapeutic or research purposes; attempts at extracorporeal fertilisation.
Manhattan geodesics and the boundary of the space of metric structures on hyperbolic groups
Authors: Cantrell Stephen , Reyes Eduardo
Published: October 2024

For any non-elementary hyperbolic group

\Gamma

, we find an outer automorphism invariant geodesic bicombing for the space of pseudometric structures on

\Gamma

equipped with a symmetrized version of the Thurston metric on Teichmüller space. We construct and study a boundary for this space and show that it contains many well-known pseudometrics. As corollaries we obtain results regarding continuous extensions of translation length functions to the space of geodesic currents and settle a conjecture of Bonahon in the negative.
Endoscopic “calabash” ligation and resection for small gastric mesenchymal tumors
Authors: Lin Xi-Min , Peng Yue-Ming , Zeng Hao-Tian , Yang Jia-Xing , Xu Zheng-Lei
Published: October 2024

BACKGROUND

Gastric mesenchymal tumors (GMT) are identified as soft tissue neoplasms that arise from mesenchymal stem cells within the gastrointestinal tract. GMT primarily encompass gastric stromal tumors (GST), gastric leiomyomas, and gastric schwannomas. Although most GMT are benign, there are still potential malignant changes, especially GST. Thus, early surgical intervention is the primary treatment for GMT. We have designed a simple endoscopic “calabash” ligation and resection (ECLR) procedure to treat GMT. Its efficacy and safety need to be compared with those of traditional endoscopic techniques, such as endoscopic submucosal excavation (ESE).

AIM

To assess the safety and effectiveness of ECLR in managing small GMT (sGMT) with a maximum diameter ≤ 20 mm by comparing to ESE.

METHODS

This retrospective analysis involved patients who were hospitalized in our institution between November 2021 and March 2023, underwent endoscopic resection, and received a pathological diagnosis of GMT. Cases with a tumor diameter ≤ 20 mm were chosen and categorized into two cohorts: Study and control groups. The study group was composed of patients treated with ECLR, whereas the control group was composed of those treated with ESE. Data on general clinical characteristics (gender, age, tumor diameter, tumor growth direction, tumor pathological type, and risk grade), surgery-related information (complete tumor resection rate, operation duration, hospitalization duration, hospitalization cost, and surgical complications), and postoperative follow-up were collected for both groups. The aforementioned data were subsequently analyzed and compared.

RESULTS

Five hundred and eighty-nine individuals were included, with 297 cases in the control group and 292 in the study group. After propensity score matching, the final analysis incorporated 260 subjects in each cohort. The findings indicated that the study group exhibited shorter operation duration and lowered medical expenses relative to the control group. Furthermore, the study group reported less postoperative abdominal pain and had a lower incidence of intraoperative perforation and postoperative electrocoagulation syndrome than the control group. There were no substantial variations observed in other parameters among the two cohorts.

CONCLUSION

ECLR is a viable and effective approach for managing sGMT.
Assessment of foot care practice among adults with diabetes mellitus in Ogbomoso, Nigeria
Authors: Idowu Adeola , Amole Isaac , Durodola Adewumi , Idowu Olatayo , Adesina Stephen , Adegoke Adepeju , Akinwumi Akinsola
Published: October 2024

Background: The prevalence of diabetes mellitus (DM) has steadily increased as also the number of people bearing its complications. One of such complications is diabetic foot disease. Foot care is an integral part of diabetes self-care and preventive strategy for reduction of diabetic foot disease and ultimate amputation.
Aim: To assess foot care practices among adults with diabetes mellitus accessing care at the Out-patient Clinic of the Bowen University Teaching Hospital, Ogbomoso, Nigeria.
Methods: This was a cross-sectional study comprising of 384 adults aged 18 years and above with diabetes mellitus of at least 6 months duration. A systematic sampling technique was used to recruit the participants for this study. Nottingham Assessment of Functional Foot Care (NAFFC) was used to assess the foot care practices of the participants. Data analysis was done using Statistical Package for Social Sciences (SPSS) version 23.
Results: Of the 384 participants recruited for the study, 321 (83.6%) had good foot care practice and 63 (16.4%) had poor foot care practice. Gender, level of education and medication use had significant association with foot care practice.
Conclusion: Foot care practice was good in majority of the participants in this study. As such, clinicians need to be consistent in providing self-foot care practice education to prevent diabetic foot diseases.
Keywords: Foot care practice; diabetic foot disease.
Sex determination and odontometric dimensions – A study of a North Indian population
Authors: Chitara Nandini , Krishan Kewal
Published: October 2024

Sex determination is an indispensable parameter in identifying unknown deceased individuals. It can narrow down the chances of possible matches by 50%, providing a crucial lead in personal identification. In cases of commingled, decomposed, fragmented, charred and unidentifiable corpses, the importance of dental morphometrics cannot be overlooked due to the resistance of teeth to post-mortem degradation. Addressing this quality of teeth, a descriptive cross-sectional study was conducted in a North Indian population to evaluate sexual variations in dental dimensions and to identify the most sexually dimorphic dental dimension. The study included 207 participants (114 females and 93 males) in the age group of 21 to 45 years. Dental casts were prepared after obtaining informed consent from the participants and ethical clearance from the institute’s ethical committee. Six odontometric dimensions, namely incisor-incisor distance, inter canine distance, combined width of central incisors, inter-premolar distance, inter-molar distance, and dental arch height of each participant were recorded on the dental casts using standard procedures. Analysis of the data elucidated the existence of statistically significant sexual dimorphism in the dental dimensions of the participants. The results of the discriminant function analysis show a sex determination accuracy of 68.1%, with a cross-validation accuracy of 65.2%. The study found the incisor-incisor distance to be the most sexually dimorphic trait, making it the best predictor of sex in the present population. The results of the present study may be helpful in sex determination and personal identification from dental remains in medico-legal and disaster victim identification cases.
Avaliação da predição de coeficientes de pressão para Edifício em H usando simulações CFD
Authors: Andrioli Medinilha de Carvalho Talita , Gimenez Juan M , Bre Facundo , Labaki Lucila Chebel
Published: October 2024

A simulação Airflow Network (AFN)/Building Energy Simulations (BES) é muito usada para incluir os efeitos da ventilação natural em análises de conforto térmico e eficiência energética. Para isso os coeficientes de pressão (Cp) são um dado de entrada importante; embora esta informação possa ser obtida através de Simulações fluidodinâmicas (CFD), estas podem apresentar incertezas, além disso, alguns modelos de cálculos podem demandar um longo tempo de processamento, como o LES (Large Eddy Simulation). A planta em formato de “H” é bastante usada em projetos arquitetônicos, sendo o estilo mais comum em residenciais multifamiliares de interesse social no Brasil. Este trabalho buscou avaliar a precisão da simulação CFD usando modelos de turbulência Reynolds-averaged Navier–Stokes (RANS: K-ω SST e RNG k-ε) para prever o valor de Cp para prédios baixos (até 4 pavimentos) e formato de “H”. Foram realizadas simulações CFD usando a plataforma CpSimulator e experimentos com modelos em escala 1:60 em túnel de vento (Laboratório Nacional de Engenharia Civil - Lisboa) para 20 ângulos de ataque do vento, reproduzindo uma camada limite atmosférica compatível com a suburbana (α=0,23). Em suma, todos os modelos de turbulências testados apresentam boa concordância com os resultados do experimento (coeficiente de determinação R2=0.9).
Contratos em IPD
Authors: Quinilato Baldessin Guilherme , Burrattino Melhado Silvio
Published: October 2024

Este estudo discute diretrizes para implementar a metodologia de Entrega de Projetos Integrados (Integrated Project Delivery - IPD) na construção civil brasileira, focando a aplicação no processo de projeto através de revisão bibliográfica e levantamento de dados com profissionais do setor, avaliando a maturidade do mercado nacional. Resultados indicam que o IPD tem a potencialidade de reduzir conflitos, melhorar a comunicação entre as partes e consequentemente, reduzir o retrabalho causado pelo planejamento descontínuo visto nas metodologias de contrato mais tradicionais. Desafios incluem falta de conhecimento sobre a metodologia por parte de contratantes e profissionais da área e resistência à mudança principalmente relacionadas ao alto custo inicial de investimento.
Quais motivadores influenciam na intenção de compra de uma habitação sustentável?
Authors: Fontolan Beatrice Lorenz , Esperidião Aline Ramos , Del Roio Iolanda Geronimo , Cardoso Raphael Alexandre de Mello , Iarozinski Neto Alfredo
Published: October 2024

Este estudo tem como objetivo identificar os fatores que impactam na disposição em adquirir uma habitação sustentável, considerando aspectos ambientais, econômicos e sociais, do ponto de vista do usuário. Um questionário foi aplicado de forma online, e uma amostra não probabilística de 163 resultados válidos foi obtida. Foram conduzidas análises estatísticas multivariadas descritivas e de correlação, utilizando o coeficiente de Spearman, com o software SPSS. As análises de correlações foram investigadas de modo a encontrar as principais relações entre 46 variáveis do grupo de motivadores e a variável “Gostaria de adquirir uma habitação sustentável”. Os resultados apresentaram seis variáveis com maior correlação positiva: Eficiência do consumo de energia; Conservação dos recursos naturais; Redução de desperdícios; Bem-estar; Redução dos impactos da edificação no meio ambiente; Aproveitamento da ventilação natural. Conclui-se que existem fatores determinantes para o sucesso na adoção de habitações sustentáveis, os quais envolvem não apenas a sustentabilidade ambiental, mas também incentivos financeiros e aspectos sociais que influenciam na tomada de decisão.
Efeito da molaridade de ácido fosfórico em geopolímeros ácidos
Authors: Hippert Júlia Amaral Ribeiro , Carvalho Aldo Ribeiro de , Oliveira Thaís Mayra de , Silva Guilherme Jorge Brigolini , Mendes Júlia Castro
Published: October 2024

Geopolímeros sintetizado em meio alcalino, a partir de hidróxido de sódio e silicato de sódio, são largamente estudados na literatura. Por sua vez, matrizes geopoliméricas desenvolvidas em meio ácido são inovações recentes, com pouco referencial teórico e muitas lacunas. O ácido fosfórico é um dos ácidos mais adotados para geopolimerização, entretanto, a sua molaridade ideal não é um conhecimento consolidado, sobretudo em matrizes de maior complexidade, como argamassas e concretos. Assim, o objetivo desse artigo é investigar os efeitos das concentrações de 8, 10 e 12 mols de ácido fosfórico na confecção de argamassas geopoliméricas desenvolvidas com metacaulim e areia natural. As argamassas produzidas foram curadas em temperatura ambiente e a 60°C. Em seguida, foi aferido o pH do material ao longo do tempo e sua resistência à compressão adquirida aos 28 dias. A partir desta análise, notou-se que quanto maior a molaridade do ácido, menor a resistência das argamassas. Além disso, ao final dos 28 dias os materiais continuaram com comportamento ácido, posto que o decaimento do pH foi irrisório.
Desenvolvimento de argamassa ecológica de alta performance com a adição de pó de gnaisse
Authors: Fajardo Abner A. , Souza Silvia R. , Almeida Fernando do Couto Rosa , Aguilar Maria Teresa P , Garcia Dayana Cristina Silva , Barbosa Maria Teresa , Santos White José dos
Published: October 2024

Analisou-se as propriedades mecânicas e de durabilidade de argamassas estruturais de alto desempenho com adição de pó de gnaisse (GN) e sílica ativa em comparação a Referência (cimento e sílica ativa) com 112 dias de idade. Realizou-se a caracterização química, física e mineralógica dos materiais. A argamassa com GN apresentou bons índices físicos (coeficiente de capilaridade de 0,06%; absorção por imersão de 0,62%, porosidade aberta de 1,41%, porosidade teórica de 0,13%), alta resistência (> 114 MPa), alta flexão (10 MPa) com um aumento da resistência à compressão de 33,50% e da tração na flexão de 61%. A resistividade elétrica superficial atingiu bons valores: 1123 kΩ.cm e a resistividade volumétrica de 1.973 Ω.m. Também ocorreu uma redução de 6,47% nas emissões de CO2 para a produção das argamassas GN em relação à argamassa REF. Conclui-se que a incorporação de pó de gnaisse em argamassas proporciona melhorias nas propriedades físicas, mecânicas e de durabilidade, além de ser ecologicamente mais sustentável.
Simulação do conforto térmico de usuários de habitações em Moçambique
Authors: Santos Lorraine Vaz Pessoa dos , Correna Carlo Joyce
Published: October 2024

O objetivo desse artigo é quantificar o conforto térmico dos usuários de habitações de baixa renda de Moçambique segundo o Zoneamento Climático proposto por meio do convênio entre a Universidade Federal de Viçosa e a Universidade Lúrio de Moçambique. Para isso, foi realizado um levantamento das habitações moçambicanas típicas nas três zonas climáticas propostas e, posteriormente, simulações termoenergéticas usando EnergyPlus. Estabeleceu-se como recorte geográfico as cidades de Nampula, Chimoio e Xai-Xai, uma cidade representativa para cada zona. Os resultados indicaram que a habitação representativa para zona climática 2, a palhota de Chimoio, apresentou maior porcentagem de horas em conforto térmico se comparada às outras habitações. Ainda, a pior situação acontece para Xai-Xai, zona climática 3. Dessa forma, os resultados contribuem para a ampliação do entendimento da realidade moçambicana no que tange habitação, além de indicar a possibilidade de aprofundamento e continuidade das investigações no campo em questão.
Susceptibilidade à fissuração de revestimentos argamassados ante ciclos térmicos
Authors: Coelho Vinicius Almeida , Omore Abraham Rodolphe Abiodoun , Freitas Priscila Verônica Galdino , Gonçalves Vanessa Gomes , Silva Francisco Gabriel Santos
Published: October 2024

As camadas dos revestimentos de fachadas estão sujeitas a variações higrotérmicas cíclicas, que podem resultar em degradação precoce ou inesperada, trazendo riscos aos usuários das edificações e elevados custos de manutenção. O presente trabalho propõe o uso de um painel radiante para simular ciclos de exposição solar de forma acelerada e avaliar a susceptibilidade de revestimentos argamassados quanto à fissuração. Após exposição térmica e resfriamento com água, observou-se a incidência e o padrão de fissuração em dois tipos de argamassa, confirmando que a técnica pode ser adotada para avaliar fatores importantes no desenvolvimento de novos produtos.
Desempenho luminoso de ambiente interno a partir de diferentes dimensões de lightscoops
Authors: Anjos Moisés Alves dos , Laranja Andréa Coelho
Published: October 2024

Aberturas zenitais tipo lightscoops podem contribuir na performance luminosa de ambientes em clima tropical úmido, com benefícios psicológicos, fisiológicos e aumento da produtividade. A pesquisa tem como objetivo investigar o desempenho luminoso de ambiente interno a partir da variação das dimensões de abertura zenital tipo lightscoops, em Vitória – ES. A metodologia abrange simulações no software Troplux 8, céu dinâmico, aberturas orientadas para Norte e Sul, das 8h30 às 16h30, todos os dias do ano. O ambiente simulado possui lightscoops na proporção de 4/3, altura e comprimento, de 5m² de área envidraçada definindo três modelos, M1, M2 e M3. As lightscoops possuem as dimensões, 2,0m x 1,5m x 2,5m; 3,0m x 2,25m x 2,5m e 4,0m x 3,0m x 2,5m, correspondendo à altura, comprimento e largura, respectivamente para M1, M2 e M3. As métricas foram os intervalos da IULN (Iluminância Útil de Luz Natural) e a ALN (Autonomia de Luz Natural). O modelo M1, para ambas as orientações, apresentou o melhor desempenho ampliando o percentual do intervalo suficiente de iluminação em cerca de 20% com relação ao modelo de pior performance, além de apresentar performance 30% superior com relação a ALN.
Indicadores normalizados para cidades sustentáveis, inteligentes e resilientes: contribuições para o Observatório do Centro de São Paulo/SP
Authors: Minozzi Pmopeo Gabriel , Miranda Catalan Henrique , Negreiros Iara , Kenya Abiko Alex
Published: October 2024

O Centro de São Paulo é uma região de suma importância para a cidade. Atualmente sistemas de dados e indicadores das cidades são apresentados por algumas cidades do mundo na forma de observatórios urbanos, definidos como instituições cujo papel está especificamente focado no conhecimento sobre assentamentos urbanos, desempenhando um papel de monitoramento explícito em termos de manter um registro regular de uma série de questões urbanas.  Visando a contribuir com a implementação do Observatório do Centro de São Paulo, uma iniciativa iniciada em 2023, este artigo apresenta uma revisão bibliográfica sobre o tema e um estudo das bases de dados disponíveis na cidade, tais como o ObservaSampa - Observatório de Indicadores da Cidade de São Paulo, e análise dos indicadores das normas NBR ISO 37120, 37122 e 37123 aplicados na região. O resultado compreende contribuições, elementos e dados para a evolução desse tema no centro urbano paulistano.