Transition mechanism design of a hybrid wheel-track-leg based on foldable rims

2019 ◽  
Vol 233 (13) ◽  
pp. 4788-4801 ◽  
Author(s):  
Faliang Zhou ◽  
Xiaojun Xu ◽  
Haijun Xu ◽  
Teng’an Zou ◽  
Lei Zhang
Keyword(s):  
Driving Force ◽  
Geometrical Property ◽  
Screw Theory ◽  
Transition Process ◽  
Performance Comparison ◽  
Dynamic Simulations ◽  
Compact Structure ◽  
Transition Mechanism ◽  
Wheel Rim ◽  
Wheel Track

Hybrid mobile robots with multiple locomotion modes are getting more and more popular in search and rescue (SAR) and explosive object disposal (EOD) missions because of their good terrain adaptability. Present researchers devote themselves to develop efficient and reliable transition method between different locomotion modes to make the hybrid robot more compact and flexible. In this paper, we present a novel transition mechanism for a hybrid wheel-track based on foldable rims. The wheel rim is cut into four segments so that it is foldable. And the transition between wheel and track is achieved by the folding or unfolding of the foldable rim. According to its geometrical property during the transition process, a single-freedom supporting spoke is proposed to drive the foldable rim’s transformation. We analyze the length and angle varying principles of the supporting spoke by utilizing the kinematic mode based on screw theory. According to above results, five different kinds of transition mechanism of the supporting spoke is designed, performance comparison among which is conducted by dynamic simulations. Two of the five candidate transition mechanisms are picked up for their smaller driving force requirements. Their 3D printing prototypes are also fabricated and experiments show that the hybrid wheel-track can switch between wheel and track successfully. Compared to most hybrid robots which have separate wheels, tracks and legs, this transition mechanism makes the robot own both compact structure and multimodal locomotion.

Place-Based Policy in the “Just Transition” Process: The Case of Polish Coal Regions

Land ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1072
Author(s):  
Aleksandra Nowakowska ◽  
Agnieszka Rzeńca ◽  
Agnieszka Sobol
Keyword(s):  
Research Methodology ◽  
Critical Analysis ◽  
Policy Making ◽  
Regional Policy ◽  
Transition Process ◽  
Information Policy ◽  
Normative Approach ◽  
Transition Mechanism ◽  
Strategic Plans ◽  
Fair Access

One of the pillars of the European Union’s Green Deal is the “Just Transition Mechanism”, which is interpreted here as providing fair access to diverse resources; above all, as a far-reaching reorientation of the approach to regional development and policy-making processes. Rooted in a normative approach to the development of just and fair place-based policy towards promoting growth in Poland, this paper aims to highlight the challenges posed by the Just Transition Mechanism in two selected Polish transition territories (Upper Silesia and Bełchatów Basin). The research methodology employs literary critical analysis along with an examination of pertinent documents, strategic plans and programs created at national and regional EU member levels. Additionally, interviews were conducted with key actors across the spectrum of the process. The authors argue that place-based policy, viewed as a new model of shaping regional policy, seeks to meet the expectations of the Just Transition Mechanism and can successfully face the challenges it encounters. The research reveals a significant gap between the analyzed transition territories in terms of knowledge and substantive preparation towards enacting the process. Visible deficits were noted in both regions concerning approaches to programming, particularly with reference to information policy and networking with partners.

scholarly journals The Influence of Wheel/Rail Contact Conditions on the Microstructure and Hardness of Railway Wheels

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Paul Molyneux-Berry ◽  
Claire Davis ◽  
Adam Bevan
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Dynamic Simulations ◽  
Near Surface ◽  
Wheel Rim ◽  
Ferrite Fraction ◽  
Proeutectoid Ferrite ◽  
Tangential Forces ◽  
Railway Wheels

The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. The in-service properties therefore vary with depth below the surface and with position across the wheel tread. This paper discusses the stress history at the wheel/rail contact (derived from dynamic simulations) and observed variations in hardness and microstructure. It is shown that the hardness of an “in-service” wheel rim varies significantly, with three distinct effects. The underlying hardness trend with depth can be related to microstructural changes during manufacturing (proeutectoid ferrite fraction and pearlite lamellae spacing). The near-surface layer exhibits plastic flow and microstructural shear, especially in regions which experience high tangential forces when curving, with consequentially higher hardness values. Between 1 mm and 7 mm depth, the wheel/rail contacts cause stresses exceeding the material yield stress, leading to work hardening, without a macroscopic change in microstructure. These changes in material properties through the depth of the wheel rim would tend to increase the likelihood of crack initiation on wheels toward the end of their life. This correlates with observations from several train fleets.

An interactive bypass transition mechanism in wall-bounded flows

2008 ◽  
Vol 615 ◽  
pp. 345-369 ◽  
Author(s):  
F. SEDAT TARDU ◽  
RABIA NACEREDDINE ◽  
OLIVIER DOCHE
Keyword(s):  
Reynolds Shear Stress ◽  
Rapid Development ◽  
Three Dimensional ◽  
Streamwise Vortex ◽  
Transition Process ◽  
Wall Turbulence ◽  
Small Scale ◽  
Bypass Transition ◽  
Transition Mechanism ◽  
Turbulent Wall

The interaction between two localized disturbances is analysed in a subcritical channel flow through direct numerical simulations. The initial perturbations are in the form of two pairs of counter-rotating vortices. One of them interacts with the wall-normal vorticity layers set up near the wall, by locally compressing or stretching part of them through the straining motion it induces. The breakdown of spanwise symmetry leads to the rapid development of a new wall-normal vorticity patch that is tilted by the shear and rolls up into a new small-scale streamwise vortex. The process results in a localized turbulent spot at later stages of development. A detailed analysis is carried out to determine the role of different parameters entering the physics of the mechanism. Several critical thresholds that trigger the interactive bypass transition process are found and analysed. The similarity parameters resulting from the parametric investigation coincide well with those governing the self-sustaining Reynolds-shear-stress-producing eddies in the buffer layer of a fully developed turbulent wall flow. It is suggested that the mechanism we propose may play a role in the regeneration cycle of the near-wall turbulence-generating structures by bypassing the three-dimensional streak instability mechanism.

scholarly journals Implementasi Jaringan Ipv6 Pada Infrastruktur Jaringan Ipv4 Dengan Menggunakan Tunnel Broker

Respati ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 1
Author(s):  
Lukman Lukman ◽  
Wahyu Adi Pratomo
Keyword(s):  
Internet Access ◽  
Transition Process ◽  
The Internet ◽  
Data Traffic ◽  
Ip Address ◽  
Ipv6 Address ◽  
Transition Mechanism ◽  
Ipv6 Network ◽  
The Many ◽  
Dual Stack

INTISARIMengakses internet adalah kegiatan yang tidak lepas dari kebutuhan masyarakat setiap hari pada saat ini. Hal tersebut dapat dilihat dari banyaknya kegiatan yang menggunakan akses internet sebagai sumber informasi dan sebagai lalu lintas data antara satu perangkat ke perangkat lainnya. Seiring berjalannya waktu semakin banyak perangkat yang membutuhkan akses internet untuk identifikasi dan definisi lokasi. Namun apakah alamat ip yang tersedia pada saat ini dapat mencukupi kebutuhan alamat ip yang semakin lama semakin bertambah akibat banyaknya perangkat yang membutuhkan alamat ip untuk mengakses internet. Jika dilihat di masa yang akan datang IPv4 yang sekarang masih kita gunakan tidak akan mencukupi kebutuhan alamat ip oleh perangkat yang digunakan. Oleh karena itu perpindahan untuk mulai menggunakan IPv6 sangatlah penting karena alamat ip IPv6 yang dihitung hampir tak terbatas dapat mencukupi kebutuhan alamat ip untuk digunakan oleh banyak perangkat. Untuk mengatasi permasalahan transisi dari IPv4 ke IPv6, Hurricane Electric ada dengan keunggulan seperti menyediakan IPv6 untuk pengguna, tanpa dipungut biaya, serta memberikan materi dan konfigurasi yang dapat digunakan oleh pengguna untuk melakukan proses transisi. Dalam proses transisi IPv4 ke IPv6 mekanisme transisi yang digunakan adalah menggunakan Tunneling, yang secara tidak langsung juga menggunakan Dual Stack karena IPv6 akan diterapkan kedalam Jaringan IPv4 yang sudah ada. Mikrotik router digunakan sebagai penghubung antara klien ke Tunnel Server dan pendelegasi IPv6 yang didapatkan dari Tunnel.Dengan pengimplementasian IPv6 ini didapatkan Hurricane Electric akan menyediakan alamat IPv6 yang bisa digunakan oleh pengguna untuk melakukan transisi Tunneling pada infrastruktur Jaringan IPv4 dan menghubungkan ke Jaringan IPv6 di internet, diharapkan banyak orang dan instasi yang akan mengerti dan memahami penggunaan dari IPv6 secara keseluruhan. Selain itu diharapkan penggunaan IPv6 juga semakin meningkat untuk menggantikan IPv4 yang sudah mulai kehabisan alamat ip untuk digunakan.Kata kunci: IPv4, IPv6, Transisi, Tunnel Broker, Hurricane Electric, Mikrotik.  ABSTRACTAccessing the internet is an activity that can not be separated from the needs of the community every day at this time. This can be seen from the many activities that use internet access as a source of information and as data traffic between one device to another. Over time more and more devices need internet access for location identification and definition. But whether the available IP address at this time can meet the need for an IP address that is increasingly growing due to the number of devices that require an IP address to access the internet. When viewed in the future, the IPv4 that we still use today will not meet the needs of the IP address of the device being used. Therefore the move to start using IPv6 is very important because the IPv6 IP address that is counted is almost unlimited can meet the needs of the IP address to be used by many devices.To overcome the problem of the transition from IPv4 to IPv6, Hurricane Electric comes with advantages such as providing IPv6 to users, free of charge, as well as providing material and configuration that can be used by users to make the transition process. In the process of transitioning from IPv4 to IPv6 the transition mechanism used is to use Tunneling, which indirectly also uses Dual Stack because IPv6 will be applied to the existing IPv4 Network. Mikrotik router is used as a liaison between the client to the Tunnel Server and IPv6 delegation obtained from the Tunnel.With the implementation of IPv6, Hurricane Electric will provide an IPv6 address that can be used by users to transition Tunneling on IPv4 Network infrastructure and connect to the IPv6 Network on the internet, it is hoped that many people and institutions will understand and understand the use of IPv6 as a whole. In addition it is expected that the use of IPv6 will also increase to replace IPv4 which has started to run out of ip addresses for use.Keywords: IPv4, IPv6, Transition, Tunnel Broker, Hurricane Electric, Mikrotik.

scholarly journals Transition mechanism of melt depth during Laser Powder Bed Fusion using in-situ X-ray and thermal imaging

2021 ◽  
Author(s):  
Tomoya Ogura ◽  
Yuki Wakai ◽  
Shizuka Nakano ◽  
Naoko Sato ◽  
Satoshi Kajino ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Thermal Imaging ◽  
Driving Force ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Molten Droplet ◽  
Recoil Pressure ◽  
Powder Bed ◽  
X Ray ◽  
Transition Mechanism

Abstract This research clarified the transition mechanism of melt depth in Ti powder bed during Laser Powder Bed Fusion process using in-situ X-ray and thermal imaging. A fiber laser beam of 150 W was irradiated on a powder bed at a scan speed of 15 mm/s for 3.5 s in a vacuum chamber. The obtained X-ray images showed a keyhole depth Ld increased immediately after laser irradiation, gradually decreased, and became constant. It also showed a keyhole width Lw increased immediately after laser irradiation and decreased afterward, after that, Lw increased again, and became constant. Furthermore, thermal images that measured the temperature on the powder bed showed the high temperature width Lh gradually increased and become constant. The model of the driving force which pushed the molten droplet was examined by analyzing the volume and scattering speed of the molten droplet. The model indicated the recoil pressure caused by the vaporization of powder metal was a driving force for the molten droplet scattering. The transition mechanism of keyhole depth was considered as follows. The increase of Ld at the beginning is due to the increase of the recoil pressure PT. This is because the decrease of Lw and large quantity of vaporization. Next, the decrease of Ld is due to the decrease in PT. This is because the increase of Lw and decrease of quantity of vaporization. At last, the transition to the constant Ld is caused by stabilization of Lw and Lh followed by stabilization of PT.

HRTEM observation of the phase transition from Bi2Sr2CaCu2O8 to Bi2Sr2Ca2Cu3O10

1990 ◽  
Vol 48 (4) ◽  
pp. 94-95
Author(s):  
Shulin Wen ◽  
F. Ernst ◽  
H. Jaeger ◽  
W. Mader ◽  
P. Majewski ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Process ◽  
Atomic Level ◽  
Point Of View ◽  
Practical Point ◽  
Transition Mechanism ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Phase Transition Process ◽  
Satisfactory Method

The investigation of the phase transiton from Bi2Sr2CaCu2O8 (2212) to Bi2Sr2Ca2Cu3O10 (2223) in the system of Bi — Sr — Ca — Cu — O is of interest both from a theoretical and a practical point of view. The result from this investigation may probably lead to a successful pure 2223 phase preparation. The preparation of pure 2223 phase with a simple and satisfactory method still remains a problem although many efforts have been made recently to produce a large percentage of 2223 phase.In order to produce pure 2223 phase most efficiently, the investigation of the transition mechanism from the 2212 to the 2223 phase is necessary. Using a JEM4000EX high resolution transmission electron microscope (HRTEM)we observed this phase transition process at atomic level. The following equation describes the phase transition from 2212 to 2223:

Compliant Mechanism Reconfiguration Based on Position Space Concept for Reducing Parasitic Motion

2015 ◽  
Author(s):  
Haiyang Li ◽  
Guangbo Hao
Keyword(s):  
Finite Element Analysis ◽  
Parallel Mechanism ◽  
Screw Theory ◽  
Compliant Mechanism ◽  
Position Space ◽  
Element Analysis ◽  
Compact Structure ◽  
Parasitic Motion ◽  
Compliant Parallel Mechanism ◽  
Space Concept

This paper introduces a compliant mechanism reconfiguration approach that can be used to minimize the parasitic motions of a compliant mechanism. This reconfiguration approach is based on the position spaces, identified by the screw theory, of independent compliant modules in a compliant mechanism system. The parasitic motions (rotations) of a compliant mechanism are first modelled associated with the variables representing any positions of the compliant modules in the position spaces. The optimal positions of the compliant modules are then obtained where the parasitic motions are reduced to minimal values. A procedure of the compliant mechanism reconfiguration approach is summarized and demonstrated using a decoupled XYZ compliant parallel mechanism as an example. The analytical results show that the parasitic motions of the XYZ compliant parallel mechanism in the example can be dramatically reduced by the position/structure reconfiguration, which is also validated by finite element analysis. The position space of a compliant module contains a number of possible positions, thus a compliant mechanism can also be efficiently reconfigured to a variety of practical patterns such as the configuration with compact structure.

DEPENDENCE OF THE PEAK EFFECT ON THE DENSITY OF PINNING SITES

2008 ◽  
Vol 22 (31) ◽  
pp. 3125-3134 ◽  
Author(s):  
I. M. OBAIDAT ◽  
U. AL KHAWAJA ◽  
M. BENKRAOUDA
Keyword(s):  
Critical Current Density ◽  
Driving Force ◽  
Peak Effect ◽  
Molecular Dynamic Simulations ◽  
Zero Temperature ◽  
Relative Height ◽  
Dynamic Simulations ◽  
One Dimensional ◽  
Matching Field

We have investigated the role of pinning density on the properties of the peak effect in the critical current density in superconducting systems. This study was conducted using a series of molecular dynamic simulations on two systems of nanostructures of periodic square arrays of pinning sites with different pining densities. We have found that the peak occurred in both systems only at zero temperature and for specific values of pinning strength. The most interesting result was that in both systems, the peak was found to occur only at nearly 0.5 fraction of the first matching field for all values of pinning strength. The properties of the peak were found to depend mainly on the initial positions of the vortices with respect to the positions of the pinning sites. The critical dipping force at the peak was found to increase linearly with the pinning strength and to have larger values for the system with the smaller density of pinning sites. The dependence of the relative height of the peak on the pinning strength was found be nearly the same in both systems. One-dimensional linear channels of moving vortices along the direction of the driving force were observed at the dip just before the peak.

scholarly journals Structural Insights into Sphingosine-1-phosphate Receptor Activation

2022 ◽  
Author(s):  
Leiye Yu ◽  
Licong He ◽  
Bing Gan ◽  
Rujuan Ti ◽  
Qingjie Xiao ◽  
...  
Keyword(s):  
Transition Process ◽  
Receptor Activation ◽  
Activation Mechanism ◽  
Structural Basis ◽  
Lymphoid Tissues ◽  
Binding Modes ◽  
Dynamic Simulations ◽  
S1p Receptors ◽  
Sphingosine 1 Phosphate ◽  
Key Steps

As a critical sphingolipid metabolite, sphingosine-1-phosphate (S1P) plays an essential role in immune and vascular systems. There are five S1P receptors, designated as S1PR1-5, encoded in the human genome, and their activities are governed by endogenous S1P, lipid-like S1P mimics, or non-lipid-like therapeutic molecules. Among S1PRs, S1PR1 stands out due to its non-redundant functions, such as the egress of T and B cells from the thymus and secondary lymphoid tissues, making it a potential therapeutic target. However, the structural basis of S1PR1 activation and regulation by various agonists remains unclear. Here we reported four atomic resolution cryo-EM structures of Gi-coupled human S1PR1 complexes: bound to endogenous agonist d18:1 S1P, benchmark lipid-like S1P mimic phosphorylated Fingolimod ((S)-FTY720-P), or non-lipid-like therapeutic molecule CBP-307 in two binding modes. Our results revealed the similarities and differences of activation of S1PR1 through distinct ligands binding to the amphiphilic orthosteric pocket. We also proposed a two-step "shallow to deep" transition process of CBP-307 for S1PR1 activation. Both binding modes of CBP-307 could activate S1PR1, but from shallow to deep transition may trigger the rotation of the N-terminal helix of Gαi and further stabilize the complex by increasing the Gαi interaction with the cell membrane. We combine with extensive biochemical analysis and molecular dynamic simulations to suggest key steps of S1P binding and receptor activation. The above results decipher the common feature of the S1PR1 agonist recognition and activation mechanism and will firmly promote the development of therapeutics targeting S1P receptors.

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