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The analysis of power flow and mechanical efficiency constitutes an important phase in the design and analysis of gear mechanisms. The aim of this paper is to present a systematic procedure for the determination of power flow and mechanical efficiency of epicyclic-type transmission mechanisms.

A novel epicyclic-type in-hub bicycle transmission, which is a split-power type transmission composed of two transmission units and one differential unit, and its clutching sequence table are introduced first. By using the concept of fundamental circuits, the procedure for calculating the angular speed of each link, the ideal torque and power flow of each link, the actual torque and power flow of each link determined by considering gear-mesh losses, and the mechanical efficiency of the transmission mechanism is proposed in a simple, straightforward manner. The mechanical efficiency analysis of epicyclic-type gear mechanisms is largely simplified to overcome tedious and complicated processes of traditionally methods.

An analysis of the mechanical efficiency of a four-speed automotive automatic transmission completed by Hsu and Huang is used as an example to illustrate the utility and validity of the proposed procedure. The power flow and mechanical efficiency of the presented 16-speed in-hub bicycle transmission are computed, and the power recirculation inside the transmission mechanism at each speed is detected based on the power flow diagram. When power recirculation occurs, the mechanical efficiency of the gear mechanism at the related speed reduces. The mechanical efficiency of this in-hub bicycle transmission is more than 96 percent for each speed. Such an in-hub bicycle transmission possesses reasonable kinematics and high mechanical efficiency and is therefore suitable for further embodiment design and detail design.

The proposed approach is suitable for the mechanical efficiency analysis of all kinds of complicated epicyclic-type transmissions with any number of degrees of freedom and facilitates a less-tedious process of determining mechanical efficiency. It is a useful tool for mechanical engineering designers to evaluate the efficiency performance of the gear mechanism before actually fabricating a prototype as well as measuring the numerical data. It also helps engineering designers to cautiously select feasible gear mechanisms to avoid those configurations with power recirculation in the preliminary design stage which may significantly reduce the time for developing novel in-hub bicycle transmissions.

The electric motor and multi-speed transmission hub are essential components for an electric bicycle. Traditionally, these two devices have been designed and manufactured independently. The purpose of this study is to propose a novel electromechanical device that artfully integrates an exterior-rotor brushless permanent-magnet (BLPM) motor into a transmission hub to become a compact structural assembly.

A novel design that integrates a three-phase, 20-pole/18-slot exterior-rotor BLPM motor with a multi-speed transmission hub composed of a six-link, two-degrees-of-freedom (2-DOF) compound planetary gear train (PGT) is presented in this study to overcome inherent drawbacks of existing designs. An analytical approach, based on fundamental circuits, is developed to synthesize the clutching sequences and numbers of teeth of all gears of the PGT.

The integrated device provides six forward speeds, including two underdrives, two direct drives, and two overdrives, as well as two drive modes: the motor-drive mode and the human-drive mode, for electric bicycles. The main feature of the proposed design is the spur gear teeth merged with the pole shoes of the stator to dramatically minimize the detent torque, which is an oscillatory torque that always induces vibration and acoustic noise of the BLPM motor.

The gear teeth on the pole shoes of the stator provide functions not only for transmission, but also act as dummy slots for adjusting the magnetostatic field of the BLPM motor to effectively reduce the detent torque. The peak value of the detent torque of the integrated design is only 9 percent of the original BLPM motor with identical magnet properties and motor dimensions. Such a feature is contributive in suppressing the vibration and acoustic noise of the electric bicycle's BLPM motor. A BLPM motor rated at 310 W and 250 r/min for the integrated device is presented and analyzed by using the commercial finite-element package Ansoft/Maxwell 2D Field Simulator.

The mischievous nodes that defy the standard corrupt the exhibition of good nodes considerably. Therefore, an intrusion discovery mechanism should be included to the mobile ad-hoc network (MANET). In this paper, worm-hole and other destructive malignant attacks are propelled in MANET.

A wireless ad-hoc network also called as mobile ad-hoc network (MANET) is a gathering of hubs that utilizes a wireless channel to exchange information and coordinate together to establish information exchange among any pair of hubs, without any centralized structure. The security issue is a major difficulty while employing MANETs.

Consequently, the attacks due to the malicious node activity are detected using Hybrid Reactive Search and Bat (HRSB) mechanism to prevent the mischievous nodes from entering the network beneath the untruthful information. Moreover, the attack detection rate and node energy are predicted for determining the lifetime of the node.

The simulation outcomes of the proposed HRSB technique are evaluated with the prevailing methods. The comparison studies have proven the efficacy of the current research model by attaining high attack detection rate and achieving more network lifetime.

OVER THE PAST TWENTY YEARS the speed of helicopters has almost doubled whilst the payload carried per pound of helicopter weight has increased more than four times. Thus the productivity of the helicopter per lb of vehicle has increased eight‐fold.

THE first prototype WG.13 Lynx made its first flight at Yeovil on 21 March, 1971, piloted by Mr W. R. Gellatly, the Chief Test Pilot of Westland Helicopters Ltd. It was the last of the three helicopters in the Anglo/French package deal to fly and the only one with design leadership on this side of the Channel. It also has the distinction of being the first new Westland design for many years. Although the Lynx looks conventional, it incorporates many technical advances, particularly noteworthy in the fundamental design of the rotor head, blades and gearbox. Notable among the new features are the semi‐rigid or hingeless rotor head, strikingly simple compared with the conventional rotor head, and the ‘conformal’ gear train which can transmit twice the power as could conventional gearing of the same size. The key factor in the design has been the requirement of reliability and this has been achieved wherever possible by simplicity.

Explains the origins of rotor aerodynamic limits for helicopters including retreating and advancing blade limits. Examines the compounding of a helicopter for higher forward speed and reports the conclusions of a student project to design a rotorcraft capable of 300 knots and carrying a payload of 30 passengers.

IN the September, 1956, issue of AIRCRAFT ENGINEERING, Mr McClements and Sq./Ldr. Armitagc surveyed ‘Helicopter Developments during the Post‐War Years’. The purpose of the present article is to discuss the subsequent developments which have taken place during the last six years. This period has been one of continued expansion in helicopter development and of much more widespread utilization of helicopters in both military and commercial operation. Since their initial development, over 150 different types of helicopter have been successfully flown. This figure includes many experimental machines or prototypes built by small groups. The major helicopter constructors have put about 40 types into quantity production and over 10,000 helicopters have been built in the Western countries. These have been predominantly for the military services, the large majority being built in U.S.A., but something approaching 2,000 have been used in commercial operations.

This paper aims to explore the evolution mechanism of resources in a standard alliance that are matched with resources required at different standardization stages from the viewpoint of dynamic matching. How core enterprises in an alliance allocate resources, select member enterprises and maintain the normal operation of an alliance, according to the resource evolution of a standard alliance, is an important issue when dealing with the implementation of technology standardization.

The authors have chosen the Intelligent Grouping and Resource Sharing (IGRS) standard alliance of computer companies in China as the object of this study. The authors have built indices to identify core enterprises in the alliance from the viewpoint of network organization. The authors also collected data from authoritative news websites concerning patents and cooperative projects undertaken by 216 enterprises in the IGRS alliance during the period from 2002 to 2016, and they have computed and analyzed these data by using UCINET 6.0 software and social network analysis methodology to identify core enterprises at different standardization stages, thus revealing the evolution mechanism for resources in the standard alliance.

Technology standardization is divided into R&D, industrialization and marketization stages, and the standard alliance requires different resources to satisfy what is required at each of those different standardization stages. While technology standardization is a process during which technology systems standards are continuously being perfected and the standard product market is continuously expanding, the development of technology standardization affects the evolutionary processes of the core enterprises and affects the selection of member enterprises in the standard alliance.

The results obtained will assist the standard alliance to select proper member enterprises and dynamically match the alliance’s resources with the resources required at different standardization stages to speed up the implementation of independent standardization in China.

This study demonstrates the evolution mechanism of resources in technology standard alliances at different standardization stages by using quantitative analysis methodology, and it enriches the research on which elements are influential for technology standardization’s development in the context of China’s social, economic and cultural characteristics.

To keep pace with demand for its revolutionary Lynx composite main rotor blade, Westland Engineering's Composites Division installed a Wild TA10BL automatic cutting table which has enabled woven details to be cut out reliably and reproducibly in a greatly reduced timescale compared with manual cutting out.