Curvature and self-assembly of semi-conducting nanoplatelets

Semi-conducting nanoplatelets are two-dimensional nanoparticles whose thickness is in the nanometer range and controlled at the atomic level. They have come up as a new category of nanomaterial with promising optical properties due to the efficient confinement of the exciton in the thickness direction. In this perspective, we first describe the various conformations of these 2D nanoparticles which display a variety of bent and curved geometries and present experimental evidences linking their curvature to the ligand-induced surface stress. We then focus on the assembly of nanoplatelets into superlattices to harness the particularly efficient energy transfer between them, and discuss different approaches that allow for directional control and positioning in large scale assemblies. We emphasize on the fundamental aspects of the assembly at the colloidal scale in which ligand-induced forces and kinetic effects play a dominant role. Finally, we highlight the collective properties that can be studied when a fine control over the assembly of nanoplatelets is achieved.

EMX2 transcriptionally regulates Nfib expression in neural progenitor cells during early cortical development.

The nuclear factor one (NFI) transcription factors play key roles in regulating the onset of both neuronal and glial differentiation during cortical development. Reduced NFI expression results in delayed differentiation, which is associated with neurodevelopmental disorders in humans that include intellectual disability, agenesis of the corpus callosum and macrocephaly. Despite their importance, our understanding of how individual NFI family members are regulated during cortical development remains limited. Here, we demonstrate that in mice, the homeobox transcription factor EMX2 regulates Nfib expression in radial glial cells during cortical development. Using a combination of bioinformatics, molecular and histological approaches, we demonstrate that EMX2 is able to bind to the Nfib promoter to up-regulate Nfib expression. Unexpectedly, in vivo over-expression of EMX2 in wildtype animals does not further up-regulate NFIB but instead leads to its down-regulation. Therefore, our findings suggest that EMX2 is capable of both activating and repressing Nfib, in a context-dependent manner. This bi-directional control over Nfib expression enables fine-tuning of the total level of NFI proteins expressed and could be important for cell-type specific NFI functions.

Definitive Dynamic MWD Surveys Generate Rig Time Savings and Flat Time Reductions in the Middle East

Wellbore surveying is a critical component of any well construction project. Understanding the position of a well in 3D space allows for the wells geological objectives to be carried out while safely avoiding other wellbores. Wellbore surveys are generally conducted using a magnetically referenced measurement while drilling tool (MWD) and taken while static, either before, after or sometimes during the connection. The drillstring is often worked to release trapped torque and time is often taken waiting for the survey to be pumped up. All of this consumes rig time and opens the wellbore up to wellbore instability issues. The application of definitive dynamic surveys (DDS) which are static MWD quality surveys taken while drilling and updated continuously. There is no longer a need to stop and take a static survey eliminating MWD surveying related rig time, reducing drilling risks from additional pumps off time and improving TVD accuracy and directional control. The rig time taken for surveying with and without DDS will be compared between similar wells in the field, and detailed analysis of relative tortuosity between DDS and non-DDS wells will also be conducted. Trajectory control analysis will be reviewed by looking at the difference in the number of downlinks between DDS and no DDS wells and also the deviation from the planned trajectory. An overall analysis of on bottom ROP will be made and an analysis as to the relative differences in TVD between static and DDS survey will be carried out. This abstract will outline the rig time and operational savings from DDS, it will detail the surveying time savings, directional control improvements, TVD placement differences to static surveys and provide costs savings as a comparison to previous similar wells. This will be outlined over a number of wells, divided by sections as the wells are batch drilled and provide an insight into the benefits of DDS on a drilling campaign. Some discussion will be made as to the efficacy of the DDS surveys and how their error model has been developed. DDS is a unique and novel way of taking surveys while drilling, providing static MWD quality without the added rig time costs but at a much higher frequency that the typical once a stand survey program. This paper outlines the cost and process savings associated with using the DDS surveys.

Lateral/Directional Control Law Design for Civil Airplane Based on Eigen Structure Assignment

Considering disadvantages of lateral/directional mode characteristics of civil aircraft, design requirements are thus presented and the P-Beta control law architecture is adopted for the lateral/directional control law. Meanwhile, the practical application of eigen structure assignment in the design of lateral/directional control law is studied. By eigen structure assignment the closed loop is designed, and the decoupling of roll channel and yaw channel is realized. Through the design of feed-forward command channel, the pilot’s stick control roll rate and pedal control sideslip angle are realized. Simulation results show that the designed lateral/directional flight control law could meet design requirements.

Direct Actuation of Large Sized Valves by a Hydraulically Relieved Electromechanical Actuation System

Extensive actuation forces and strokes are required for the actuation of large sized valves normally implemented in high power hydraulic systems. A hydraulically piloted operation is, for now, the most suitable solution and state of the art. However, there are some applications where electromechanical valve actuation systems are at advantage against common pilot operation systems. In this contribution it is analyzed in which cases the application of electro-mechanical actuators can be of advantage and why displacement-controlled systems may be one of these applications. A novel electromechanical valve actuation system for large sized 4/3-way directional control valves for the use in displacement-controlled systems is presented. This new actuation system is characterized by a hydraulic relief of the centering springs. Therefore, the springs are only active in safety-critical conditions, such as a power outage. Since the actuator is not working against the spring force during every displacement, the necessary actuation force is reduced drastically. Thus, common electromechanical actuators can be used. In case of a power outage, the spring relief is deactivated causing the stored energy to center the spool in its neutral position. The performance of the novel actuation system is examined through measurements conducted on a manufactured demonstrator for valves of nominal size 25 with a flow rate of up to 600 l/min.

Development of Surface EMG Game Control Interface for Persons with Upper Limb Functional Impairments

In recent years, surface Electromyography (sEMG) signals have been effectively applied in various fields such as control interfaces, prosthetics, and rehabilitation. We propose a neck rotation estimation from EMG and apply the signal estimate as a game control interface that can be used by people with disabilities or patients with functional impairment of the upper limb. This paper utilizes an equation estimation and a machine learning model to translate the signals into corresponding neck rotations. For testing, we designed two custom-made game scenes, a dynamic 1D object interception and a 2D maze scenery, in Unity 3D to be controlled by sEMG signal in real-time. Twenty-two (22) test subjects (mean age 27.95, std 13.24) participated in the experiment to verify the usability of the interface. From object interception, subjects reported stable control inferred from intercepted objects more than 73% accurately. In a 2D maze, a comparison of male and female subjects reported a completion time of 98.84 s. ± 50.2 and 112.75 s. ± 44.2, respectively, without a significant difference in the mean of the one-way ANOVA (p = 0.519). The results confirmed the usefulness of neck sEMG of sternocleidomastoid (SCM) as a control interface with little or no calibration required. Control models using equations indicate intuitive direction and speed control, while machine learning schemes offer a more stable directional control. Control interfaces can be applied in several areas that involve neck activities, e.g., robot control and rehabilitation, as well as game interfaces, to enable entertainment for people with disabilities.

Model development and simulation of vehicle suspension system with magneto-rheological damper

A vehicle suspension system is designed to maintain directional control (road holding) during manoeuvring or braking while supporting the vehicle’s weight and provide stability (handling). The structure of a suspension system consists of parts connecting the axle to wheel assembly and the chassis of an automobile, thus supporting engine, transmission system and vehicle load. Suspension system components consist of dampening devices, springs, steering knuckles, ball joints and spindles or axles. It could be designed according to a passive, semi-active or active mode of working. For evaluation, this assembly could be modelled as a spring-mass-damper system. The semi-active suspension system has been modelled with a magneto-rheological damper following the Bingham plastic theory. In this paper, the performance of a passive and a semi-active suspension of a quarter car model are compared by MATLAB simulation. Thus, a better suspension system is found out by simulating with different road conditions.

Quasi-Static Research of ATV/UTV Non-Pneumatic Tires

The non-pneumatic tire (NPT) is a type of wheel whichdevelopment is related to the beginning of automotive development. The non-pneumatic tire (NPT) is a type of tire that does not contain compressed gases or fluid to provide directional control and traction. Nowadays, this type of wheel is more and more often used in special purpose vehicles, e.g., in military vehicles and working machines. The main feature of the non-pneumatic tire is a flexible support structure (including the part of the wheel between the tread and the rim). This paper presents the results of research aimed at determining the influence of the geometry of the NPT’s (intended for All-Terrain Vehicle - ATV / Utility Task Vehicle - UTV) load-bearing structure on its quasi-static directional characteristics. The experimental tests included the determination of the radial stiffness of research objects on a non-deformable flat surface and on a single obstacle, as well as the determination of the degree of deformation for the elastic structure and belt. The significant influence of the elastic structure’s shape and the elastomer, as the material forming the NPT, on its radial stiffness was revealed.