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In this study, for the first time, the efficacy of control rods for full suppression of vortex-induced vibrations (VIV) and galloping of an elastically supported rigid square cylinder that vibrates freely in the cross-flow direction is investigated.

To this aim, two small control rods are placed at constant angles of ± 45° relative to the horizontal axis and then the influence of diameter and spacing ratios on the oscillation and hydrodynamic response along with the vortex structure behind the cylinder is evaluated in the form of nine different cases in both VIV and galloping regions.

The performed simulations show that using the configuration presented in this study results in full VIV suppression for the spacing ratios G/D = 0.5, 1 and 1.5 at the diameter ratios d/D = 0.1, 0.2 and 0.3 (D: diameter of square cylinder, G: distance between rods and cylinder, d: diameter of rods). On the contrary, a perfect attenuation of galloping is only achieved at the largest diameter (d/D = 0.3) and the smallest spacing ratio (G/D = 0.5). In general, for both VIV and galloping regions, with increasing diameter ratio and decreasing spacing ratio, the effect of the control rods wake in the vortex street of square cylinder gradually increases. This trend carries on to the point where the vortex shedding is completely suppressed and only the symmetric wake of control rods is observed.

So far, the effect of rod control on VIV of a square cylinder and its amplitude of oscillations has not been investigated.

During drilling in coal mines, sticking of drill rod (referred to as SDR in this work) is a potential threat to underground safety. However, no practical measures to deter SDR have been developed yet. The purpose of this study is to develop an anti-SDR strategy using proportional-integral-derivative (PID) and compliance control (PIDC). The proposed strategy is compatible with the drilling process currently used in underground coal mines using drill rigs. Therefore, this study aims to contribute to the PIDC strategy for solving SDR.

A hydraulic circuit to reduce SDR was built based on a load-independent flow distribution system, a PID controller was designed to control the inlet hydraulic pressure of the rotation motor and a typical compliance control approach was adopted to control the feed force and displacement. Moreover, the weight and optimal combination of the alternative admittance control parameters for the feed cylinder were obtained by adopting the orthogonal experiment approach. Furthermore, a fuzzy admittance control approach was proposed to control the feed displacement. Experiments were conducted to test the effectiveness of the proposed method.

The experimental results indicated that the PIDC strategy was appropriate and effective for controlling the rotation motor and feed cylinder; thus, the proposed method significantly reduces the SDR during drilling operations in underground coal mines.

As the PIDC strategy solves the SDR problem in underground coal mines, it greatly improves the safety of coal mine operation and decreases the power cost. Consequently, it brings the considerable benefits of coal mine production and vast application prospects in other corresponding fields. Actual drilling conditions are difficult to accurately simulate in a laboratory; thus, for future work, drilling experiments can be conducted in actual underground coal mines.

The PIDC-based anti-SDR strategy proposed in this study satisfactorily controls the rotation motor and feed cylinder and facilitates the feed and rotation movements. Furthermore, the tangible novelty of this study results is that it improves the frequency response of the entire drilling system. The drilling process with PIDC decreased the occurrence of SDR by 50%; therefore, the anti-SDR strategy can significantly improve the safety and efficiency of underground coal mining.

Minimally invasive surgery (MIS) is a cost‐effective alternative to the open surgery whereby essentially the same operations are performed using specialized instruments designed to fit into the body through several tiny punctures instead of one large incision. The EndoBots (Endoscopic Robots) described here are designed for collaborative operation between the surgeon and the robotic device. The surgeon can program the device to be operated completely manually, collaboratively where motion of the robotic device in certain directions is under computer control and in others under manual surgeon control, or autonomously where the complete device is under computer control. Furthermore, the robotic tools can be quickly changed from a robotic docking station, allowing different robotic tools to be used in an operation.

MASS production methods in the construction of modern aircraft demand far‐reaching standardization of such component parts as can be used in various types of aeroplane. Such standardization has, for instance, been applied to the power plant control rods of the Ju 52 where a unified design of welded steel levers is found together with standardized shafts. That type of construction has given very satisfactory results on the whole though improvements have been made here and there to keep abreast of the general advance in aircraft design and of the development of fabricating methods. The standardized rigging thus evolved responds to practical requirements in that the number of parts has been reduced to a minimum so as to allow of a maximum of combinations and to cut down the number of spares to be kept in store. Such demands were chiefly made by the German Air Force since interchangeability of parts is, of course, a factor of primary importance to ensure simplification of supply services and ease of maintenance of the first line fleet in case of an emergency. Moreover, plain bearings for moving parts had proved unsatisfactory in service as they necessitated frequent inspection and lubrication. The only way out of that difficulty was to employ ball bearings through‐out to reduce friction to an absolute minimum and to eliminate lubrication altogether.

Presents numerical algorithms which easily solve both optimal distributed and optimal boundary control problems in a space‐time domain. Analyses two simple cases of continuous systems. These are the vibrating string and the axially vibrating rod. Using finite difference recurrence schemes, gives numerical results which compare the behaviour of the controlled and uncontrolled systems. Compares the results for special cases in which analytical solutions are obtainable are compared with the results using the general numerical schemes.

THE normal control surfaces of an aeroplane are the elevator (for pitching); the rudder (for yawing); and the ailerons (for rolling). In certain cases the ailerons may be replaced or augmented by spoilers, conveniently placed just in front of the ailerons, or at the same chordal position further inboard.

BEFORE commencing an inspection obtain the pilot's report on the previous flight. In the course of the following inspections, as with all inspections, components which are found to be damaged or defective must be repaired, if possible, or replaced. However, before repairing a component, the relevant repair instructions must be consulted. Unless otherwise stated, these inspections are carried out every 40 hours.

THE Tiger VIII is an air‐cooled, two‐row, radial engine with fourteen cylinders. A two‐speed supercharger is enclosed in the induction case, and the engine is designed for use with a V.P. airscrew. In moderately supercharged form it develops 805–845 b.h.p. at 6,250 ft., while the fully supercharged type develops 725–760 b.h.p. at 12,750 ft.

THE A300B employs fully powered flying controls, operated by hydraulic power, with no reversion to manual control. The hydraulic power supplies are ‘triplexed’ to the banks of three jacks at each primary control surface. Jack sizes are chosen so that full control over the flight envelope is available with only two hydraulic systems working. Should a further system have to be shut down for any reason, the one remaining set of jacks will still provide sufficient power for control of the aircraft, including landing.