Rack and Pinion Steering System Design for a Passenger Car

The steering system plays a crucial role in the stability of the automobile, especially in the safety of the passengers and pedestrians. The aim of this work is to design a rack and pinion steering system that could equip a passenger car. In this process, many parameters are considered for the correct and effective directional response behavior of the vehicle. 2D models were sketched to validate the kinematic algorithm calculus used to optimize and refine the dimensions of the components of the steering system. After a satisfactory Ackermann percentage was achieved, steering system is designed and analysed in one of the most used CAD and CAE software in automotive, CATIA.

Upstream rheotaxis of catalytic Janus spheres

Fluid flow is ubiquitous in many environments that form habitats for microorganisms. The tendency of organisms to navigate towards or away from flow is termed rheotaxis. Therefore, it is not surprising that both biological and artificial microswimmers show responses to flows that are determined by the interplay of chemical and physical factors. In particular, to deepen understanding of how different systems respond to flows, it is crucial to comprehend the influence played by swimming pattern. In recent studies, pusher-type Janus particles exhibited cross-stream migration in externally applied flows. Earlier, theoretical studies predicted a positive rheotactic response for puller-type spherical Janus micromotors. To compare to a different swimmer, we introduce Cu@SiO2 micromotors that swim towards their catalytic cap. Based on experimental observations, and supported by flow field calculations using a model for self-electrophoresis, we hypothesize that they behave effectively as a puller-type system. We investigate the effect of externally imposed flow on these spherically symmetrical Cu@SiO2 active Janus colloids, and we indeedobserve a steady upstream directional response. Through a simple squirmer model for a puller, we recover the major experimental observations. Additionally, the model predicts a unique “jumping” behaviour for puller-type micro- motors at high flow speeds. Performing additional experiments at high flow speeds, we capture this phenomenon, in which the particles “roll” with their swimming axes aligned to the shear plane, in addition to being dragged down- stream by the fluid flow.

Development of neutron survey meter using prescila neutron probe

This paper presents the design and validation of a neutron survey meter. The meter consists of a PRESCILA neutron probe (with good sensitivity, directional response, gamma rejection, and enhanced high-energy response to 20 MeV) and an electrometer developed at Non-Destructive Evaluation center. The homogeneity response of the PRESCILA neutron probe was investigated as a function of distances from the 241Am - 9Be source in order to obtain the appropriate distance for accurate count-rate measurements using the neutron survey meter. A system consists of the PRESCILA neutron probe and the Ludlum Model 2326 electrometer was then used for measuring neutron ambient dose equivalent rates in the range from 50 cm to 200 cm with the step of 25 cm. The relationship between the count-rates and neutron dose equivalent rates (in the distance ranged from 50 to 200 cm) were deduced to validate the proper operation of the neutron survey meter.

Agonistic experience during development establishes inter-individual differences in approach-avoidance behaviour of crickets

Members of numerous animal species show consistent inter-individual differences in behaviours, but the forces generating animal “personality” or individuality remain unclear. We show that experiences gathered solely from social conflict can establish consistent differences in the decision of male crickets to approach or avoid a stimulus directed at one antenna. Adults isolated for 48 h from a colony already exhibit behavioural differences. Prior to staging a single dyadic contest, prospective winners approached the stimulus whereas prospective losers turned away, as they did also after fighting. In contrast, adults raised as nymphs with adult males present but isolated from them as last instar nymphs, all showed avoidance. Furthermore, adults raised without prior adult contact, showed no preferred directional response. However, following a single fight, winners from both these groups showed approach and losers avoidance, but this difference lasted only one day. In contrast, after 6 successive wins or defeats, the different directional responses of multiple winners and losers remained consistent for at least 6 days. Correlation analysis revealed examples of consistent inter-individual differences in the direction and magnitude of turning responses, which also correlated with individual aggressiveness and motility. Together our data reveal that social subjugation, or lack thereof, during post-embryonic and early adult development forges individuality and supports the notion of a proactive–reactive syndrome in crickets.

The Use of Chemical Cues by Sargassum Shrimps Latreutes fucorum and Leander tenuicornis in Establishing and Maintaining a Symbiosis with the Host Sargassum Algae

A mutualistic symbiosis exists between the alga Sargassum spp. and two shrimp species, Latreutes fucorum and Leander tenuicornis. However, little is known about how these shrimp locate and establish their host alga. Both visual and chemical cues are potentially available. A previous study has looked at both cue variables with results that are mixed. Specifically, these same shrimp species used chemical cues only when visible cues were available simultaneously. Visual cues would be presumably restricted at night, but chemical cues are potentially available continuously. This current research elaborates on the previous study to fully understand Sargassum shrimp chemoreception. Increases in sample sizes and both a 4-chambered and Y-maze apparatus were used to test whether the shrimp could detect Sargassum cues, dimethylsulfoniopropionate (DMSP) (a chemical excreted by some marine algae), and conspecific cues. Neither shrimp species showed a strong directional response to any of the chemical cues, but the Sargassum and DMSP cues did cause more shrimp to exhibit searching behavior. Additionally, several differences in responses between male and female shrimp were found for each cue. A lowered dilution of DMSP was also tested to determine sensitivity of L. fucorum shrimp to the chemical cue; although searching behavior was triggered, conclusions about quantifying the sensitivity could not be made. Overall, these results show the shrimp can detect chemical cues—in the absence of visual cues—that could affect initiating and maintaining this shrimp/algal symbiosis.

Improving the Directional Behavior of PDC Bits Affected by Stick-Slip: A Statistical Approach

Torsional vibrations are a very common phenomenon affecting drilling operations by limiting efficiency, increasing the risk of downhole equipment failure and generating additional costs, particularly when their most severe form is encountered, the stick-slip. It is less known that torsional vibrations also strongly affect directional drilling operations reducing directional stability and tool face control. In this paper, the highly variable solicitation induced by torsional vibrations is addressed with a statistical approach. This approach, used successfully in Kuwait applications, resulted in an operational savings of 30% of the cost per foot over a panel of more than 15 runs analyzed. Steerability and directional stability is critical on directional wells, especially when using push-the-bit systems with PDC bit due to side force distributed unevenly over one bit revolution. Most of today bit design comparisons are made with an average steerability factor computed over one full revolution of the bit. The method described in this paper is going further in details and looks at the evolution of directional performance indicators within one bit revolution. With the help of a state-of-the-art 3D bit-rock interaction model, which simulates the drilling environment considering the drive system mechanism and both the drill bit and the hole being drilled as a set of 3D meshed surfaces, an accurate picture of the directional stability of the bit design is available. This approach is complemented by a statistical analysis which allows to simulate a multitude of input parameters combinations and to map the directional response of a bit design in a more robust way. Based on the results of the statistical analysis, an optimized design was selected and manufactured for a 12 ¼’-in. rotary steerable system (RSS) directional application known for having torsional vibration limitations. As revealed by the simulation results, this design was expected to exhibit a better directional stability than previous bit design iterations. This optimized design was run on RSS and positive displacement motor (PDM) assemblies and successfully drilled several wells in different fields of Kuwait operations ground. It experienced smooth and stable directional control while reducing the risk for torsional vibrations and resulted in tremendous reduction of the overall cost per foot. PDC bit selection and design process have considerably evolved in the last decade with the use of increasingly accurate simulations models. This paper presents the next step of evolution dedicated to delivering the best adapted solution to any given scenario by examining in greater detail the directional response of a drill bit.