Abstract
This paper proposes a guidance law based on trajectory prediction, aiming to address the difficulty of traditional guidance laws in meeting high-speed and highly maneuverable vehicles. The ...unscented Kalman filtering (UKF) technique is employed to estimate the target’s motion and predict the virtual impact point using the Singer model and measuring model. The midcourse guidance law is applied to the virtual target, taking into account the constraint of the intersection angle, while the terminal guidance utilizes modified proportional guidance. To mitigate the overload chattering in the transition sections of both midcourse and terminal guidance, the distance is used to modify the transition section of the terminal guidance. Simulation results demonstrate that the proposed guidance law effectively reduces both the encounter angle and the required maneuvering. Furthermore, to minimize midcourse guidance errors, the prediction results of the virtual target are continually updated during the trace process. This method can also be applied to trail other highly maneuverable targets.
Great research efforts have been invested in developing nerve guidance conduits (NGCs), which can direct axons advance and guide peripheral neural regeneration. Here, three different aspects of NGC ...design, namely anisotropy, photocatalytic stimulation and self-assembly at implantation site, were unitedly addressed. Firstly, melt electrowriting (MEW) was used to print anisotropic, microfibrous PCL architectures. Specifically, by tailoring the fiber spacing ratio between two arms of the grid patterns (1-1, 1–2, 1–3), preferential neurite extension of PC 12 cells along the long arm direction was achieved. Such anisotropic neurites guidance was further strengthened when the intersection angles were reduced from 90° to 30°. Secondly, functionalization of PCL micropatterns with graphene oxide and graphitic carbon nitride (g-C3N4), a visible-light photocatalyst, may enable optoelectronic conversion and wireless neural stimulation. As a result, photocatalytic stimulation further enhanced neurite extension length under visible light irradiation. Last but not the least, NGC were successfully obtained either by manually rolling or self-assembly using a thermo-responsive bi-layer system. Interestingly, the anisotropic micropattern design dictated the self-assembly process, and an underlying mechanism was proposed. With a synergy of three unique design parameters, the herein presented NGCs may possess great potential for repairing peripheral nerve injuries.
Biophysical cues including anisotropic topography guidance and photocatalytic stimuli are incorporated into a 3D polymeric scaffold, by precise topography control via MEW technique and post-decoration of photocatalyst g-C3N4. The versatile scaffold with anisotropic patterned structure highly accelerates and leads to preferential neurite outgrowth, revealing its great potential for working as NGCs to enhance peripheral neural regeneration. Display omitted
Activities in the field of automated driving have produced a variety of development tools and methodologies over the past decades. The requirements the systems have to fulfil and thus also the ...development guidelines are often documented in different kinds of catalogues (use-case catalogues, situation catalogues, scenario catalogues etc.). These catalogues cannot be directly applied for the development of partially and highly automated vehicle guidance concepts like conduct-by-wire (CbW) or H-mode. One reason is that up to now, no consistent terminology known to the authors yet exists for vehicle automation within the community. Moreover, as the aim of the two project groups CbW and H-mode is to make a comprehensive feasibility assessment of cooperative vehicle guidance, all interacting components of the overall system as well as all potential driving conditions a cooperative vehicle guidance system might have to cope with have to be analysed. This article focuses on two aspects. The first is a metaphor-based terminology discussion leading to a proposal for a fundamental ontology. The second aspect is an outlook on the different catalogues that use the new terminology and that have been developed. The methodology introduced here is a fundamental contribution towards simplifying communication and the exchange of findings.
Research has consistently shown that inquiry-based learning can be more effective than other, more expository instructional approaches as long as students are supported adequately. But what type of ...guidance is adequate, and for whom? These questions are difficult to answer as most previous research has only focused on one type of guidance and one type of learner. This meta-analysis therefore synthesized the results of 72 studies to compare the effectiveness of different types of guidance for different age categories. Results showed facilitative overall effects of guidance on learning activities (d = 0.66, 95% CI 0.44, 0.88), performance success (d = 0.71, 95% CI 0.52, 0.90), and learning outcomes (d = 0.50, 95% CI 0.37, 0.62). Type of guidance moderated the effects on performance success but not on the other two outcome measures. Considerable variation was found in the effects of guidance on learning activities, but the relatively low number of studies do not allow for any definitive conclusion on possible agerelated differences.
Guided internet-based treatment is more efficacious than completely unguided or self-guided internet-based treatment, yet within the spectrum of guidance, little is known about the added value of ...human support compared to more basic forms of guidance. The primary aims of this meta-analysis were: (1) to examine whether human guidance was more efficacious than technological guidance in text-based internet treatments (“e-therapy”) for mental disorders, and (2) whether more intensive human guidance outperformed basic forms of human guidance. PsycINFO, PubMed and Web of Science were systematically searched for randomized controlled trials that directly compared various types and degrees of online guidance. Thirty-one studies, totaling 6215 individuals, met inclusion criteria. Results showed that human guidance was slightly more efficacious than technological guidance, both in terms of symptom reduction (g = 0.11; p < .01) and adherence (0.26 < g < 0.29; p's < 0.01). On the spectrum of human support, results were slightly more favorable for regular guidance compared to optional guidance, but only in terms of adherence (OR = 1.89, g = 0.35; p < .05). Higher qualification of online counselors was not associated with efficacy. These findings extend and refine previous reports on guided and unguided online treatments.
•Human guidance is more efficacious than technological guidance in text-based internet treatments for mental disorders.•Regular (‘weekly’) human guidance is more efficacious than optional human guidance in terms of adherence.•Higher frequency or speed of human guidance is not more efficacious than regular human guidance.•Qualification of online counselors is not associated with efficacy.
Considering the requirements of saturation attack, a time-coordination entry guidance algorithm for multi-hypersonic vehicles is proposed in this paper, which is composed of three parts: generation ...of coordination time, predictive lateral guidance based rough adjustment of reentry flight time and longitudinal predictor-corrector guidance based time coordination. Firstly, the coordination flight time is generated by analyzing the time range of entry flight for each hypersonic vehicle. Next, in the lateral profile, the predictive lateral guidance is employed to roughly adjust the reentry flight time of the vehicle, and provide feasible time range of coordinative flight for longitudinal predictor-corrector guidance. In the longitudinal profile, a quadratic bank angle magnitude profile is designed and adjusted by the Newton iteration scheme to meet the range and time constraints, and realize the time-coordination entry guidance for multi-hypersonic vehicles. As the impacts of the lateral motion and longitudinal motion on entry flight time are both considered, the proposed algorithm greatly extends the feasible time range of coordinative flight, which is more suitable for engineering practice. Finally, the feasibility and robustness of the proposed time-coordination entry guidance algorithm are tested and verified by the multi-mission and multi-vehicle guidance simulations.
ABSTRACTCareer guidance counsellors’ competence requirements in Norwegian schools have been the subject of decades-long discussion. Practitioners, experts, and stakeholders have called for precise ...requirements and professionalized status for counsellors, but with little results. In the Finnish context, however, career guidance is more professionalized, and the counsellor competence requirements are defined by law. Why have the two systems developed differently? In this research, we used ‘historical institutionalism’ as our lens and compared the two developmental histories of the counsellor role and the reasoning behind these differentiating systems. By utilizing Toulmin’s model of argumentation, we analysed rationales in policy documents from ministries to expert groups to reveal how the policy rationales have formed the different statuses of the career counsellor profession in the 1950s, 1960s and 1990s. Norway and Finland saw the counsellor role similarly, but eventually, decisions on qualifications and competency were made from different perspectives.
This paper proposes a novel approach for guidance law design to satisfy the impact-time constraints for a certain class of homing missiles. The proposed guidance law provides proper lateral ...acceleration commands that make the impact time error converge to zero by the time of impact. This scheme can be applied to any existing guidance law for which a formula of predicted time to go is available. Convergence of time-to-go errors is supported by Lyapunov stability. The optimal guidance law and the impact angle control guidance law are extended by the proposed method for impact-time-control guidance and impact-time-and-angle-control guidance, respectively. The performance of the extended guidance laws is demonstrated by numerical simulation.
This article presents a target-enclosing guidance law for an autonomous vehicle to enclose a stationary target within arbitrary smooth geometrical shapes or patterns in 3-D, thereby presenting a ...generic guidance strategy for target-enclosing behavior. We particularly focus on designing a target-enclosing strategy wherein the vehicle does not have radial acceleration capabilities and is steered by its lateral acceleration only. Such consideration makes the design appealing for aerial vehicles with turning constraints. The proposed design accounts for the coupled 3-D engagement, thereby preventing performance degradation when the pitch and the yaw channels are decoupled into two separate and mutually orthogonal planar engagements. We further evaluate the lateral acceleration components of the vehicle in the orthogonal (pitch and yaw) channels by minimizing the instantaneous total control effort subject to an affine constraint. We demonstrate the effectiveness and advantages of the proposed controller through simulations.
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