How to assess the accuracy of the individual tree-based forest inventory derived from remotely sensed data: a review

Effort has been devoted to automatic or semi-automatic individual tree detection and crown delineation from remotely sensed data, aiming at the effective creation of forest inventory, to assist forest management and ecosystem modelling. However, there is no uniform evaluation scheme to assess the resulting products. This paper reviews the available techniques and essential considerations for evaluating remote sensing-based forest inventory products, including detected individual tree locations, crown delineation maps, forest structure parameters, and species classification results. The reference data collection, individual tree matching method, mismatched individual tree crown treatment, and stratification criteria are summarized as four key factors in the evaluation process. Additionally, a discussion of future working directions, regarding limitations of existing techniques, multi-scale evaluation, sampling schemes, uncertainty analysis, and results interpretation, is also included. A new accuracy assessment framework is proposed, and an accuracy report example is provided.     

Compact see‐through near‐eye display with depth adaption

Based on the recent development of Pancharatnam–Berry deflectors and lenses, we propose a compact and lightweight near‐eye display system with depth adaption. The compact design results from the polarization selectivity of Pancharatnam–Berry deflector waveguide coupler, and the fast‐switching Pancharatnam–Berry lenses can be exploited for generating correct light fields.     

重轨热锯机变速技术应用

介绍了鞍钢股份有限公司大型厂热锯机为满足产品多样化需要,实现热锯机变速功能的软硬件配置情况,着重介绍了各种变速方案具体设计思想及优缺点以及最终实施的方案。通过介绍PLC内程序的编写和SIEMENS数控器的设置,详细阐述了变速技术的实现原理。     

Adaptive variable universe of discourse fuzzy control for a class of nonlinear systems with unknown dead zones

In this paper, based on an adaptive nonbackstepping design algorithm, we proposed a novel variable universe of discourse fuzzy control (VUDFC) approach for a class of single‐input–single‐output strict‐feedback nonlinear systems with unknown dead‐zone inputs. Firstly, we convert the form of system into a normal form on the basis of some new state variables and coordinate transformation; at the same time, state‐feedback control is changed to output‐feedback control. Secondly, we design observers to estimate the new unmeasurable states. Then, different from considering the traditional backstepping‐based fuzzy control scheme, we introduce a direct VUDFC scheme, which is mainly based on changing of contraction‐expansion factors to modify the universe of discourse online, and fuzzy rules can automatically reproduce to develop the control performance; thus, the size of initial rule base is greatly reduced. This new algorithm can alleviate tracking error, improve the accuracy of the system, and strengthen robustness. Lastly, according to Lyapunov theorem analysis, we prove that all the signals in the closed‐loop system can be guaranteed to be stable, and the output can track the reference signal very well. Simulation results illustrated the effectiveness of the proposed VUDFC approach.     

Subspace Methods with Local Refinements for Eigenvalue Computation Using Low-Rank Tensor-Train Format

Computing a few eigenpairs from large-scale symmetric eigenvalue problems is far beyond the tractability of classic eigensolvers when the storage of the eigenvectors in the classical way is impossible. We consider a tractable case in which both the coefficient matrix and its eigenvectors can be represented in the low-rank tensor train formats. We propose a subspace optimization method combined with some suitable truncation steps to the given low-rank Tensor Train formats. Its performance can be further improved if the alternating minimization method is used to refine the intermediate solutions locally. Preliminary numerical experiments show that our algorithm is competitive to the state-of-the-art methods on problems arising from the discretization of the stationary Schrödinger equation.     

Synchrotrons radiation stability measurement and improvement

In the 3rd generation synchrotron light source,beside the orbit,air disturbance and ground vibration also could affect the position stability of photon beam in synchrotrons radiation measurement.In the condition of implementation of orbit feedback system at SSRF,the measured position stability of photon beam in synchrotrons radiation measurement station was presented in this paper.And then the improvement methods of position stability of photon beam were discussed.Finally the measured result was shown when the designed feedback system is implemented to improve the position stability of photon beam.     

预制装配式混凝土盖梁的研究与应用综述

装配式装配式施工已成为城市桥梁建设的发展趋势。然而，交通需求巨大的城市宽桥通常会有大量的下部结构承台。盖梁的长度往往大于25米，重量通常超过300吨。整体预制盖梁的运输条件受道路限制，整体吊装吨位过大。盖梁预制装配技术得到了广泛的重视和迅速的发展。本文对盖梁预制装配技术进行了分类，并介绍了典型的工程实例。总结了预制盖梁的性能研究现状，总结了盖梁预制装配技术存在的不足和改进方向。     

Synthesis of soluble and thermally stable poly(N‐arylenebenzimidazole)s

Six new bis(benzimidazolyl) monomers containing ether, sulfonyl and ketone groups were synthesized efficiently. A series of poly(N‐arylenebenzimidazole)s were prepared using an aromatic nucleophilic displacement reaction that removed the N–H sites from the novel bis(benzimidazolyl) derivatives with activated aromatic difluorides in sulfolane. The reaction was carried out at 210 °C in the presence of anhydrous potassium carbonate. All resulting polymers showed essentially amorphous patterns. This was consistent with the calculated results. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>240 °C), good thermostability and high decomposition temperatures (>400 °C). These novel polymers also showed easy solubility. © 2013 Society of Chemical Industry     

采用萘系高效减水剂试制免蒸压高强混凝土管桩

在优化管桩混凝土配合比的基础上,采用萘系高效减水剂和高活性矿物掺合料生产了免蒸压高强混凝土管桩,并将产品用于实际施工中。结果证明,该管桩的生产工艺简单、成本较低、性能良好,对节能减排和环境保护具有重要的意义。