Directional Steering Research Articles

Deterministic photon-emitter coupling in chiral photonic circuits.

Engineering photon emission and scattering is central to modern photonics applications ranging from light harvesting to quantum-information processing. To this end, nanophotonic waveguides are well suited as they confine photons to a one-dimensional geometry and thereby increase the light-matter interaction. In a regular waveguide, a quantum emitter interacts equally with photons in either of the two propagation directions. This symmetry is violated in nanophotonic structures in which non-transversal local electric-field components imply that photon emission and scattering may become directional. Here we show that the helicity of the optical transition of a quantum emitter determines the direction of single-photon emission in a specially engineered photonic-crystal waveguide. We observe single-photon emission into the waveguide with a directionality that exceeds 90% under conditions in which practically all the emitted photons are coupled to the waveguide. The chiral light-matter interaction enables deterministic and highly directional photon emission for experimentally achievable on-chip non-reciprocal photonic elements. These may serve as key building blocks for single-photon optical diodes, transistors and deterministic quantum gates. Furthermore, chiral photonic circuits allow the dissipative preparation of entangled states of multiple emitters for experimentally achievable parameters, may lead to novel topological photon states and could be applied for directional steering of light.

The Role of Performance Management in the Steering of Executive Agencies: Layered, Imbedded, or Disjointed?

ABSTRACTThis article analyzes the Norwegian state administration’s performance management practices, based on a study of performance contracts between 77 Norwegian executive agencies and their parent ministries. The results show that most performance objectives target agency outputs and outcomes, suggesting that the “right version” of performance management is practiced. Two perspectives are developed to hypothesize about performance management’s relationship to legal, fiscal, legal, and direct behavioral steering. The layering perspective assumes that ministries use performance management to repair gaps left by limitations in the other control instruments. The imbedding perspective assumes that ministries develop performance management practices that uphold intentions for delegated autonomy. The layering perspective receives some support, but overall it seems that decisions about how to use each governance instrument are quite disjointed, without much concern for harmony with how other instruments are used. The article also shows that performance management practices are influenced by contextual factors like the number of tasks an agency performs, organizational heterogeneity, and whether an agency was established before or after the general introduction of performance management.

Asymmetric quantum network based on multipartite Einstein–Podolsky–Rosen steering

In this work, we propose an asymmetric multi-user access optical network with hierarchical structure in terms of steering ability. The N-partite system is generated by mixing two squeezed lights and N−2 vacuum modes at N−1 beam splitters. The asymmetry of this system can be constructed by choosing proper reflectivities of beam splitters and introducing asymmetric loss to channels of the network, such that the steering ability is distributed asymmetrically among users. By proper construction, one superior in the network possesses higher steering ability than any one of the remaining N−1 subordinates. We show how to accomplish the directional quantum steering between them, i.e., the superior can apparently steer any subordinate’s state, but it cannot always happen in the opposite direction. In addition, we quantify the thresholds of loss tolerance that will prevent the extraction of information of the superior by M(1≤M≤N−1) subordinates’ local measurements. An important feature of such a network is that the superior can send a secret message to certain subordinates without trustworthy assumptions about them and their apparatus. Our findings have applications in one-sided device-independent quantum communication protocol with multi-users.

Directional Recording of Subthalamic Spectral Power Densities in Parkinson's Disease and the Effect of Steering Deep Brain Stimulation.

A new 32-contacts deep brain stimulation (DBS) lead, capable of directionally steering stimulation, was tested intraoperatively. The aim of this pilot study was to perform recordings from the multidirectional contacts and to investigate the effect of directional current steering on the local field potentials (LFPs). In eight patients with Parkinson's disease, after standard microelectrode recording and clinical testing, the new lead was temporarily implanted. The 32-channel LFP recordings were measured simultaneously at different depths and directions before and after directional stimulation. The spatial distribution of LFPs power spectral densities across the contact array at baseline marked the borders of the subthalamic nucleus (STN) with a significant increase in beta power and with a mean accuracy of approximately 0.6mm in four patients.The power in the 18.5-30Hz frequency band varied across different directions in all patients. In the three cases that showed improvement of rigidity, this was higher when current was steered toward the direction with the highest LFP power in the beta band. Subthalamic LFPs in six patients showed a differential frequency-dependent suppression/enhancement of the oscillatory activity in the 10-45Hz frequency band after four different 'steering' modes as compared to ring mode, suggesting a higher specificity. Through a new 32-contact DBS lead it is possible to record simultaneous subthalamic LFPs at different depths and directions, providing confirmation of adequate lead placement and multidirectional spatial-temporal information potentially related to pathological subthalamic electrical activity and to the effect of stimulation. Although further research is needed, this may improve the efficiency of steering stimulation.

Multipartite Einstein–Podolsky–Rosen steering and genuine tripartite entanglement with optical networks

The Einstein-Podolsky-Rosen (EPR) paradox established a link between entanglement and nonlocality in quantum mechanics. EPR steering is the nonlocality associated with the EPR paradox and has traditionally only been investigated between two parties. Here, we present the first experimental observations of multipartite EPR steering, and of the genuine tripartite continuous variable entanglement of three mesoscopic optical systems. We explore different linear optics networks - each one with optimised asymmetries - that create multipartite steerable states containing different numbers of quantised optical modes (qumodes). By introducing asymmetric loss on a 7-qumode state, we characterize 8 regimes of directional steering, showing that N + 1 regimes exist for an N-qumode state. Further, we reveal the directional monogamy of steering, and experimentally demonstrate continuous variable one-sided semi device-independent quantum secret sharing. Our methods establish principles for the development of multiparty quantum communication protocols with asymmetric observers, and can be extended to qubits, whether photonic, atomic, superconducting, or otherwise.

NMR Structure Reveals Novel Interactions between Intrinsically Disordered PEP-19 and Calmodulin

Background: PEP-19 has no known intrinsic activity other than binding predominately to the C-domain of calmodulin (C-CaM), yet it is implicated in numerous cellular processes. We showed that an acidic sequence in PEP-19 is required to greatly increase the rates of Ca2+ binding to C-CaM. Importantly, the acidic sequence is also required for PEP-19 to sensitize HeLa cells to ATP-induced Ca2+ release. Goal: The goal of the current study was to determine the high-resolution NMR solution structure of the PEP-19/apo C-CaM complex.Results: Apo C-CaM adopts a semi-open conformation when bound to PEP-19, with the helices E and F of Ca2+ binding site III showing the greatest change in angle relative to free apo C-CaM. The conformation of Ca2+ binding loop III is similar to that in free apo C-CaM, but loop IV adopts a different conformation with increased conformational exchange when bound to PEP-19. Residues 1-29 in PEP-19 remain disordered when bound to C-CaM, and are thus accessible for potential interactions with other proteins. The IQ motif in PEP-19 adopts a well-defined alpha helix that binds to a hydrophobic groove in apo C-CaM. The C-terminal part of the acidic sequence is alpha helical, but the N-terminal portion (aa 28-36) forms loop and coil structures that are stabilized by interactions between Ile32 and Met34 in PEP-19 and hydrophobic residues in Ca2+ binding site III of C-CaM. This allows acid side chains in PEP-19 to extend toward the solvent to greatly increase negative charge density near site III of C-CaM.Conclusions: The structure suggests that the acidic sequence in PEP-19 modulates Ca2+ binding to site III of C-CaM by direct interactions and/or electrostatic steering of Ca2+, but that allosteric effects increase conformational exchange to modulate Ca2+ binding to site IV.

Integrated control of automobile ABS/DYC/AFS for improving braking performance and stability

Braking control on a μ-split road is not an easy task. An integrated control (ITC) algorithm is proposed by combining antilock braking system (ABS), direct yaw-moment control (DYC) and active front steering (AFS). The algorithm is intended for maximising the utilisation of road friction while maintaining directional stability of a vehicle during emergency braking on a μ-split road. A three-layer hierarchical control architecture is developed for the ITC. The upper-layer controller is used for DYC to generate a desired yaw moment, allocation of the moment to ABS and AFS is handled by the intermediate-layer controller, and two control algorithms are designed at the lower-layer for ABS and AFS, respectively. The performance of the ITC is compared with a modified independent control (MIC) algorithm via hardware-in-the-loop (HIL) simulations. The results show that the braking performance and stability of the vehicle are improved by employing the ITC algorithm.

Assessing Steering Feel in Truck Drivers: Evaluation Criteria and Rating Scale

In the past, steering feel in trucks was a compromise between acceptable steering torques at low velocities and a direct steering feel at higher velocities. Today, steering characteristics can be specifically adapted to the current driving situation due to the use of electric power steering systems. Following the human-centred design for interactive systems (ISO 9241-210) [1], the end user of a product must be included into the development process. Thus, a questionnaire to measure steering feel in truck drivers was designed. Therefore, evaluation criteria were derived from interview studies (N = 76 drivers) and the literature. Afterwards, vehicle dynamics experts supplied them with specific descriptions to maximize comprehensibility and determined the ideal situations in which the criteria can be assessed. Based on another interview study (N = 98 drivers) and a subsequent cluster analysis, the criteria were allocated to dimensions of steering feel. Lastly, a driving study (N = 41 drivers) was conducted to evaluate and further improve the questionnaire. In future research, it can be used to measure and optimize steering feel from the truck drivers’ perspective.

Internal models direct dragonfly interception steering.

Sensorimotor control in vertebrates relies on internal models. When extending an arm to reach for an object, the brain uses predictive models of both limb dynamics and target properties. Whether invertebrates use such models remains unclear. Here we examine to what extent prey interception by dragonflies (Plathemis lydia), a behaviour analogous to targeted reaching, requires internal models. By simultaneously tracking the position and orientation of a dragonfly's head and body during flight, we provide evidence that interception steering is driven by forward and inverse models of dragonfly body dynamics and by models of prey motion. Predictive rotations of the dragonfly's head continuously track the prey's angular position. The head-body angles established by prey tracking appear to guide systematic rotations of the dragonfly's body to align it with the prey's flight path. Model-driven control thus underlies the bulk of interception steering manoeuvres, while vision is used for reactions to unexpected prey movements. These findings illuminate the computational sophistication with which insects construct behaviour.

Health System Strengthening Interventions to Improve Maternal Health in India

BACKGROUND: India alone accounts for 17% of the global maternal deaths, which is the highest for any single country in the world. Sadly, India is unlikely to meet the Millennium development Goal 5 by 2015. Several interventions have been undertaken in last decade to improve maternal health situation in India, however often discrete and dispersed. Health system’s perspective is important to re-align and direct these interventions towards common system goals that result in strengthening of health system on one hand and on the other hand, provides a strong and robust platform for interventions to operate, making latter effective, targeted, scalable and sustainable. AIMS: To study key interventions those strengthen different health system components to improve maternal health in India, in the way to the achievement of MDG5, to reflect upon their achievements and gaps for further research, programmatic and policy implications. METHODOLOGY: A multiple database search provided the academic studies for a literature review. Study included interventions targeted only on mothers who are in - pregnancy, childbirth or the post-partum period in Indian setting. Recent impact assessment studies (2009-2014) that have outcomes related to maternal health are included. A WHO health systems framework comprising of six building blocks is used to study these interventions from health system’s perspective. RESULTS: India has a strong political will to bring about the change much yearned; however an integrated and directional steering is warranted. Preliminary success of financing schemes that increase demand of health services by providing financial protection in some states sets good example, yet replicating these achievements nation-wide needs a defined structure with a common vision. Addressing workforce shortages by varied strategies is a good beginning, however their effectiveness in long run and scalability is yet to be established. Albeit experimenting with new approaches of monitoring and evaluating maternal deaths and its causes, a dependable and integrated system to track maternal deaths and assess effect of interventions on maternal deaths is urgently needed. Conclusion: A health system’s approach not only integrate interventions that are otherwise haywire but also establish coordination and interaction between different components of interventions delivering an amplified effect.

Directional Steering Technique Development Trend of the Directional Drilling in the Oil and Gas Fields

방향성 및 수평시추는 상업적인 비전통자원개발에 있어서 아주 중요한 기술로 자리잡았다. 이러한 시추기술을 가능케 하는 방향제어기술은 꾸준히 발전되어 왔다. 1990년대에, 비전통자원개발 현장에서 요구되는 복잡한 시추궤도와 수평 장공시추를 위해 공저이수모터와 RSS를 이용한 방향제어 기술이 도입 되었으며, 최근에는 PRSS와 하이브리드 RSS를 이용하는 기술로 발전되었다. 이와 같은 방향제어 기술의 발전으로 수 km에 이르는 수평 장공시추가 가능하게 되었으며, 이로 인하여 오늘날 북미의 셰일가스 및 오일 개발이 활성화 될 수 있었다. 본 연구에서는 방향제어 기술들의 원리와 장단점을 기술발전의 과정과 함께 고찰하였다. 또한 각 기술별 적용 시 고려할 점을 살펴보았다.

Independent Torque Control of an Independent-Wheel-Drive Electric Vehicle

This paper focuses on designing a controller to enhance the traction and handling of an Independent-Wheel-Drive Electric Vehicle (IWD-EV). It presents a traction torque distribution controller for an IWD-EV in order to maintain vehicle handling and stability during critical maneuvers. The proposed controller is based on the Direct Yaw-moment Control (DYC) and Active Front Steering control (AFS) which intended to increase the handling and stability of the vehicle respectively by applying the yaw rate and the lateral acceleration as the control variables. The performance of the controller is evaluated by numerical simulations of two standard high speed maneuvers which are the double lane change (DLC) and J-Curve. The proposed scheme presents a new controller design for IWD-EV which can effectively improved the vehicle handling and stability.

Directional steering: A novel approach to deep brain stimulation.

The aim of this study was to investigate whether directional steering through a novel 32-contact electrode is safe and can modulate the thresholds for beneficial and side effects of stimulation. The study is a single-center, performance and safety study. Double-blind intraoperative evaluations of the thresholds for therapeutic benefit and for side effects were performed in 8 patients with Parkinson disease while stimulating in randomized order in spherical mode and in 4 different steering modes with the 32-contact electrode, and in monopolar mode with a commercial electrode. In addition, simultaneous recordings of local field potentials through all 32 contacts were performed. There were no adverse events related to the experimental device. For 13 of 15 side effects (87%), the threshold could be increased by ≥ 1 mA while steering in at least one direction in comparison to conventional spherical stimulation, thereby increasing the therapeutic window by up to 1.5 mA. Recording local field potentials through all 32 electrode contacts yielded spatiotemporal information on pathologic neuronal activity. Controlled steering of current through the brain may improve the effectiveness of deep brain stimulation (DBS), allow for novel applications, and provide a tool to better explore pathophysiologic activity in the brain. This study provides Class IV evidence that for patients with Parkinson disease, steering DBS current is well tolerated, increases the threshold for side effects, and may improve the therapeutic window of subthalamic nucleus DBS as compared with current standard spherical stimulation.

Switching strategies for narrow ground vehicles with dual mode automatic tilt control

A tall and narrow type of commuter vehicle has an increased tendency to overturn during hard cornering when compared to conventional vehicles. This tendency can be mitigated by tilting it toward the inside of the turn. Two types of automatic tilting control strategies have been developed: Direct Tilt Control (DTC) and Steering Tilt Control (STC). At zero or low speeds, the DTC provides torque on the body to keep the body upright. The STC provides at high speeds lower perceived lateral acceleration and possibly a more natural feel for the passengers. The two types of tilt control cannot operate simultaneously without interfering with each other so here the problem of switching from one to the other without introducing disturbing transients is studied. In general, the switch from DTC to STC occurs as a specific speed is attained but we also show how the system can switch back to DTC for safety reasons under a low traction patch of roadway in a turn.

Silicon nitride waveguide router enabling directional power transmission

A passive guided-wave router featuring directional power transmission among three different input/output ports has been proposed and demonstrated, taking advantage of appropriately disposed straight and bent waveguides in silicon nitride. The proposed router consists of a straight waveguide and a curved waveguide of the same width, which are brought together with a small offset between them and are interconnected together to another curved waveguide of an enlarged width. Due to the passively directional steering of excited guided modes induced by the device configuration, a three-port guided wave router is demonstrated where a signal input from Port I passes to Port II, but a signal fed from Port II is directed to Port III instead of Port I, providing a good contrast level of 14dB at λ=1546nm for forward and backward transmissions. Insertion losses of 4.6dB and 1.2dB were respectively obtained for the routes from Port I to Port II and from Port II to Port III. Due to the absence of active control and the use of conventional linear materials, the proposed passive router featuring a compact configuration will play a pivotal role in creating fully functional on-chip photonic circuits.

Communication in Automotive Networks Illustrated with an Example of Vehicle Stability Program: Part I - Control Area Network

AbstractThe design of DAS (Direct Adaptive Steering) systems has been used in aviation for a long time. A few months ago a Japanese automotive company, Nissan Motor Co, for the first time introduced a steer-by-wire (no mechanical connection between the steering wheel and the front wheels of the car) solution - to the automotive world in their Infiniti Q50 car. This article aims to explain the issues related to controlling the car automation system, in which one of the control parameters is the examined turn of the wheels assigned by the driver (or the DAS system).

Highly Directional Emission and Beam Steering from Organic Light‐Emitting Diodes with a Substrate Diffractive Optical Element

Highly directional emission from an organic light-emitting diode (OLED) is demonstrated by out-coupling the substrate mode from a Eu-based OLED using a diffractive optical element embedded in the substrate. This approach gives emission that is confined in a single narrow cone with FWHM divergence of 15° or less, which is very different from the normal Lambertian emission of OLEDs.

Study on a New Steering Mechanism for Point-the-Bit Rotary Steerable System

This paper presents a novel steering mechanism embedded in a point-the-bit rotary steerable system (RSS) for oilfield exploitation. The new steering mechanism adopts a set of universal joints to alleviate the high alternative strain on drilling mandrel and employs a specially designed planetary gear small tooth number difference (PGSTD) to achieve directional steering. Its principle and characteristics are explained and examined through a series of analyses. First, the eccentric displacement vector of the offset point on the drilling mandrel is formulated and kinematic solutions are established. Next, structural design for the new steering mechanism is addressed. Then, procedures and program architectures for simulating offset state of the drilling mandrel and motion trajectory of the whole steering mechanism are presented. After that, steering motion simulations of the new steering mechanism for both 2D and 3D well trajectories are then performed by combining LabVIEW and SolidWorks. Finally, experiments on the steering motion control of the new steering mechanism prototype are carried out. The simulations and experiments reveal that the steering performance of the new steering mechanism is satisfied. The research can provide good guidance for further research and engineering application of the point-the-bit RSS.

Dynamic Beam Steering from a Subwavelength Slit by Selective Excitation of Guided Modes

Dynamic control of the direction of radiation of the light emanating from a subwavelength slit carved out of a thin metal film is experimentally demonstrated. This is achieved by selective excitation of the individual guided modes in the slit by setting the phase of three coherent laser beams. By changing the voltage across a piezoelement, we obtain unprecedented directional steering, without relying on any mechanical alignment of optical elements. The angular range over which this maximum can be swept is determined by the intensity setting of one of the incident beams. Through simulations, we show that this method can also be applied to steer the radiation from a square hole in two independent directions. Our method can be applied to create a directional nanoemitter which can selectively address one or more detectors, or as an optical switch in photonic circuits.

Dynamic Analysis and Simulation of a New Steering Mechanism for Point-the-Bit Rotary Steerable System

In oilfield exploitation, automatically directional steering can only be achieved with rotary steerable system (RSS). The designed well trajectories have become more complicated e.g. horizontal wells, extended reach drilling wells and 3D multi-target wells. To drill these complicated wells, new drilling tools are urgently needed. This paper proposed a new steering mechanism for point-the-bit RSS. The new steering mechanism uses a set of universal joints to avoid the high alternative strain on drilling mandrel, and it uses a specific eccentric planetary gear train to offset the drilling mandrel to achieve directional steering. Design procedure, Solid modeling, Force analysis and dynamic simulation have been discussed for further dynamic analysis towards the confirmation of the steering performance.