A method for the reduction of aerodynamic drag of road vehicles

A method is proposed for the reduction of the aerodynamic drag of bluff bodies, particularly for application to road transport vehicles. This technique consists of installation of panels on the forward surface of the vehicle facing the airstream. With the help of road tests, it was demonstrated that the attachment of proposed panels can reduce aerodynamic drag of road vehicles and result in significant fuel cost savings and conservation of energy resources

Selective AP-sequence Based Indoor Localization without Site Survey

In this paper, we propose an indoor localization system employing ordered sequence of access points (APs) based on received signal strength (RSS). Unlike existing indoor localization systems, our approach does not require any time-consuming and laborious site survey phase to characterize the radio signals in the environment. To be precise, we construct the fingerprint map by cutting the layouts of the interested area into regions with only the knowledge of positions of APs. This can be done offline within a second and has a potential for practical use. The localization is then achieved by matching the ordered AP-sequence to the ones in the fingerprint map. Different from traditional fingerprinting that employing all APs information, we use only selected APs to perform localization, due to the fact that, without site survey, the possibility in obtaining the correct AP sequence is lower if it involves more APs. Experimental results show that, the proposed system achieves localization accuracy < 5m with an accumulative density function (CDF) of 50% to 60% depending on the density of APs. Furthermore, we observe that, using all APs for localization might not achieve the best localization accuracy, e.g. in our case, 4 APs out of total 7 APs achieves the best performance. In practice, the number of APs used to perform localization should be a design parameter based on the placement of APs.Comment: VTC2016-Spring, 15-18 May 2016, Nanjing, Chin

End-To-End Simulation of Launch Vehicle Trajectories Including Stage Separation Dynamics

The development of methodologies, techniques, and tools for analysis and simulation of stage separation dynamics is critically needed for successful design and operation of multistage reusable launch vehicles. As a part of this activity, the Constraint Force Equation (CFE) methodology was developed and implemented in the Program to Optimize Simulated Trajectories II (POST2). The objective of this paper is to demonstrate the capability of POST2/CFE to simulate a complete end-to-end mission. The vehicle configuration selected was the Two-Stage-To-Orbit (TSTO) Langley Glide Back Booster (LGBB) bimese configuration, an in-house concept consisting of a reusable booster and an orbiter having identical outer mold lines. The proximity and isolated aerodynamic databases used for the simulation were assembled using wind-tunnel test data for this vehicle. POST2/CFE simulation results are presented for the entire mission, from lift-off, through stage separation, orbiter ascent to orbit, and booster glide back to the launch site. Additionally, POST2/CFE stage separation simulation results are compared with results from industry standard commercial software used for solving dynamics problems involving multiple bodies connected by joints

Constraint Force Equation Methodology for Modeling Multi-Body Stage Separation Dynamics

This paper discusses a generalized approach to the multi-body separation problems in a launch vehicle staging environment based on constraint force methodology and its implementation into the Program to Optimize Simulated Trajectories II (POST2), a widely used trajectory design and optimization tool. This development facilitates the inclusion of stage separation analysis into POST2 for seamless end-to-end simulations of launch vehicle trajectories, thus simplifying the overall implementation and providing a range of modeling and optimization capabilities that are standard features in POST2. Analysis and results are presented for two test cases that validate the constraint force equation methodology in a stand-alone mode and its implementation in POST2

Application of an Optimal Control Allocation Scheme with Structural Load and Aero Heating Feedback for a Morphing Inflatable Aerodynamic Decelerator

Precision landing of large payloads on Mars presents a challenge to the Entry, Descent, and Landing (EDL) community. Previous studies indicated that by incorporating the capability for a Hypersonic Inflatable Aerodynamic Decelerator (HIAD) to morph during reentry would result in a more accurate landing footprint by allowing modulation of the lift- to-drag (L/D) vector directly instead of through bank angle control. However, morphing the HIAD shape for trajectory control may expose the HIAD to potential structural loads or aero heating concerns. In this study, the application of an optimal control allocation (OCA) technique was investigated that would to enable the morphing HIAD to maximize trajectory control capabilities while simultaneously keeping the structural loads and aero heating below some thresholds. This concept was demonstrated in a 3 degree-of-freedom (DOF) EDL simulation and provides basis for future research

Penerapan Strategi Pembelajaran Problem Posing Tipe Post Solution Posing Untuk Meningkatkan Kemampuan Penalaran Dan Keberanian Bertanya Matematika (PTK Pada Siswa Kelas X Semester Ganjil SMK Muhammadiyah 5 Purwantoro Tahun Ajaran 2012/ 2013)

Penelitian ini bertujuan untuk meningkatkan Penalaran dan Keberanian bertanya siswa dalam pembelajaran matematika melalui strategi Problem Posing Tipe Post Solution posing. Jenis Penelitian ini adalah Penelitian Tindakan Kelas. Subyek penerima tindakan adalah siswa kelas XBB di SMK Muhammadiyah 5 Purwantoro yang berjumlah 32 siswa Perempuan. Metode pengumpulan data dilakukan melalui wawancara, observasi, catatan lapangan, tes dan dokumentasi. Teknik analisis data dilakukan secara deskriptif kualitatif dengan analisis interaktif. Hasil penelitian ada peningkatan Penalaran dan Keberanian bertanya siswa dalam pembelajaran matematika tentang materi ajar Operasi pada bilangan real. Hal ini dapat dilihat dari indikator penelitian 1. Penalaran Siswa : a) Menyajikan pernyataan matematika secara lisan, sebelum tindakan 15,6%, setelah tindakan 71,9%, b) Mengajukan dugaan atau ide, sebelum tindakan 18,8%, setelah tindakan, 78,1%, c) Melakukan manipulasi matematika atau menyusun bukti, sebelum tindakan 18,8%, setelah tindakan 75%, d) Kemampuan membuktikan kesahihan suatu argument, sebelum tindakan 21,9%, setelah tindakan 78,1%, e) Kemampuan menarik kesimpulan logis, sebelum tindakan28,1, setelah tindakan 81,3%. 2.Keberanian bertanya Siswa : a) Mau mencoba hal – hal yang baru, sebelum tindakan 15,6%, setelah tindakan 75%, b) Mau mengemukakan pendapat, sebelum tindakan 18,8%, setelah tindakan 78,1%, c) Mampu mengendalikan rasa takut dalam bertanya, sebelum tindakan 18,8%, setelah tindakan 81,3%, d) Mampu menghadapi tantangan, sebelum tindakan 21,9, setelah tindakan 78,1%. Penelitian ini menyimpulkan bahwa penerapan strategi Problem posing tipe post Solution Posing dapat meningkatkan Penalaran dan Keberanian bertanya siswa dalam pembelajaran matematika tentang Operasi Pada Bilangan Real

Modeling Multibody Stage Separation Dynamics Using Constraint Force Equation Methodology

This paper discusses the application of the constraint force equation methodology and its implementation for multibody separation problems using three specially designed test cases. The first test case involves two rigid bodies connected by a fixed joint, the second case involves two rigid bodies connected with a universal joint, and the third test case is that of Mach 7 separation of the X-43A vehicle. For the first two cases, the solutions obtained using the constraint force equation method compare well with those obtained using industry- standard benchmark codes. For the X-43A case, the constraint force equation solutions show reasonable agreement with the flight-test data. Use of the constraint force equation method facilitates the analysis of stage separation in end-to-end simulations of launch vehicle trajectorie

Verification of a Constraint Force Equation Methodology for Modeling Multi-Body Stage Separation

This paper discusses the verification of the Constraint Force Equation (CFE) methodology and its implementation in the Program to Optimize Simulated Trajectories II (POST2) for multibody separation problems using three specially designed test cases. The first test case involves two rigid bodies connected by a fixed joint; the second case involves two rigid bodies connected with a universal joint; and the third test case is that of Mach 7 separation of the Hyper-X vehicle. For the first two cases, the POST2/CFE solutions compared well with those obtained using industry standard benchmark codes, namely AUTOLEV and ADAMS. For the Hyper-X case, the POST2/CFE solutions were in reasonable agreement with the flight test data. The CFE implementation in POST2 facilitates the analysis and simulation of stage separation as an integral part of POST2 for seamless end-to-end simulations of launch vehicle trajectories

Simulation and Analyses of Multi-Body Separation in Launch Vehicle Staging Environment

The development of methodologies, techniques, and tools for analysis and simulation of multi-body separation is critically needed for successful design and operation of next generation launch vehicles. As a part of this activity, ConSep simulation tool is being developed. ConSep is a generic MATLAB-based front-and-back-end to the commercially available ADAMS. solver, an industry standard package for solving multi-body dynamic problems. This paper discusses the 3-body separation capability in ConSep and its application to the separation of the Shuttle Solid Rocket Boosters (SRBs) from the External Tank (ET) and the Orbiter. The results are compared with STS-1 flight data

Aerodynamic Analyses and Database Development for Ares I Vehicle First Stage Separation

This paper presents the aerodynamic analysis and database development for first stage separation of Ares I A106 crew launch vehicle configuration. Separate 6-DOF databases were created for the first stage and upper stage and each database consists of three components: (a) isolated or freestream coefficients, (b) power-off proximity increments, and (c) power-on proximity increments. The isolated and power-off incremental databases were developed using data from 1% scaled model tests in AEDC VKF Tunnel A. The power-on proximity increments were developed using OVERFLOW CFD solutions. The database also includes incremental coefficients for one BDM and one USM failure scenarios