SIMULASI NUMERIK KENDALI KAPAL CEPAT TAK BERAWAK DUA PROPELLER TANPA RUDDER

This paper discusses the simulation of automation control and hull manufacturing on a fast boat. This high-speed boat that will be carried out for fish mapping. This study uses a numerical simulation to predict its motion. The experiment was carried out 3 times in forward motion, and 3 times in turn motion. The ship’s time and movement in ideal conditions will be recorded for each experiment. With the PID value for forward overshoot with values such as: 8.94%, 30.86%, and 40.60%, while turning overshoot is obtained, among others: 25.77%, 49.82%, and 61.15% Then the advanced settling time obtained includes: 0.91 seconds, 3.84 seconds, and 5.31 seconds. The settling time for turns is: 1,022 seconds, 0.85 seconds, and 0.84 seconds These values are obtained from the simulation graph of the three-dof formulas for surge, sway, yaw.

AERODYNAMIC LIFT FORCES ON MULTIHULLED MARINE VEHICLES

The need for high-speed high-payload craft has led to considerable efforts within the marine transport industry towards a vehicle capable of bridging the gap between conventional ships and aircraft. One such concept uses the forward motion of the craft to create aerodynamic lift forces on a wing-like superstructure and hence, reduce the displacement and skin friction. This paper addresses the specific aerodynamic design of multihull for optimal lift production and shows that significant efficiency can be achieved through careful shaping of a ducted hull, with lift-to-drag ratios of nearly 50 for a complete aerodynamic hull configuration. Further analysis is carried out using a hybrid vehicle stability model to determine the effect of such aerodynamic alleviation on a theoretical planing hull. It is found that the resistance can be halved for a fifty metre, three hundred tonne vehicle with aerodynamic alleviation travelling at 70 knots. Results are presented for a candidate vessel.

Nanopore tweezers measurements of RecQ conformational changes reveal the energy landscape of helicase motion

Helicases are essential for nearly all nucleic acid processes across the tree of life. Using Nanopore Tweezers we observed the small, fast steps taken by single RecQ helicases as they step along and unwind DNA at ultrahigh spatiotemporal resolution. By directly measuring conformational substates of RecQ we determine the coupling between helicase domain motions and chemical reactions that together produce forward motion along the DNA. Application of assisting and opposing forces shows that RecQ has a highly asymmetric energy landscape that reduces its sensitivity to opposing mechanical forces that could be encountered in vivo by molecular roadblocks such as DNA bound proteins. This energy landscape enables RecQ to maintain speed against an opposing load.

Travels and Trials of Climate Knowledge in Finnish Municipalities

We examine why implementing climate aims has proven challenging for municipalities. Recognising that climate policy research identifies ‘barriers’ to the forward motion of environmental knowledge, we use STS tools to dismantle ‘barrier thinking’ and analyse the dynamics of climate knowledge in municipal organisations. The primary data are 21 interviews with climate change and risk management experts in Finnish municipalities. We employ the idea of ‘trials of strength’ to analyse not mere barriers but gatherings, translations, and implementations of environmental knowledge. We argue that four kinds of trials are crucial in transforming climate knowledge so it can cohere with ongoing processes: it is gathered and condensed at the organisation’s borders; climate experts embody and transmit the knowledge; meeting tables form obligatory passage points for its implementation; and road maps draw actors together to circulate it. While traveling around municipal organisations, climate knowledge is often sidetracked but can sometimes become unexpectedly effective.

DYNAMIC ANALYSIS OF BOGIE WHEELSET- A REVIEW

The dynamic of railway vehicle wheelsets is influenced by the actions of the conicity of the wheels and the creep forces acting between the wheels and rails. In this review paper, the dynamics analysis of wheelset has investigated, equations of motion have formulated and stability criteria obtained which indicate the effects of varying the various parameters of the system. The nature of the motion at the critical speed is investigated and the mode of energy conversion between the forward motion of the vehicle and the lateral motion of the wheelset is explained. From a dynamic analysis, it is shown how the critical speed of the wheelset slips and suspension stiffness relates to the kinematic motion.

Can Optic Flow Further Stimulate Treadmill-Elicited Stepping in Newborns?

Typically developing 3-day-old newborns take significantly more forward steps on a moving treadmill belt than on a static belt. The current experiment examined whether projecting optic flows that specified forward motion onto the moving treadmill surface (black dots moving on the white treadmill surface) would further enhance forward stepping. Twenty newborns were supported on a moving treadmill without optic flow (No OF), with optic flow matching the treadmill’s direction and speed (Congruent), with optic flow in the same direction but at a faster speed (Faster), and in a control condition with an incoherent optic flow moving at the same speed as in the Congruent condition but in random directions (Random). The results revealed no significant differences in the number or coordination of forward treadmill steps taken in each condition. However, the Faster condition generated significantly fewer leg pumping movements than the Random control condition. When highly aroused, newborns made significantly fewer single steps and significantly more parallel steps and pumping movements. We speculate the null findings may be a function of the high friction material that covered the treadmill surface.

Catapult start likely improves sprint start performance

Sprint technical training, named the catapult start, is defined as partner assisted pulling of the hip backward at the set position and during block clearance, released by the forward motion of the athlete. This study investigated the characteristics of the catapult start and its influence on the following sprint start performance. Fourteen male sprinters performed a single 15-m control, catapult, and post-catapult sprint starts, during which ground reaction forces (GRFs) were measured using force platforms. All measured GRF variables during the block clearance, except for the impulses and mean forces on the front block and ratio of force for the rear block, were greater in the catapult start than the control (effect size [ES]=0.52–2.09). Waveform analyses revealed that the rear block anteroposterior GRF was greater for the catapult start than the control during the initial, middle and final phases (0 to 20%, 40 to 61% and 95 to 100%) of block clearance, while the rear block ratio of force was greater for the catapult start until 13% of block clearance. The catapult start resulted in greater rear block ratio of force (ES = 0.28), faster 10-m sprint time (ES = 0.31) and greater average horizontal external power during the initial 10-m (ES = 0.25) at the post-catapult trial. The results suggest that the catapult start can be accompanied with greater force production mainly for the rear block regardless of direction during the block clearance, and it can improve post-catapult sprint start performance in terms of the rear block ratio of force and 10-m sprint time.