Defects Detection and Assessment in Concrete Surfaces

Aside from cracks, the impact of other surface defects, such as air pockets and discoloration, can be detrimental to the quality of concrete in terms of strength, appearance and durability. For this reason, local and national codes provide standards for quantifying the quality impact of these concrete surface defects and owners plan for regular visual inspections to monitor surface conditions. However, manual visual inspection of concrete surfaces is a qualitative (and subjective) process with often unreliable results due to its reliance on inspectors’ own criteria and experience. Also, it is labor intensive and time-consuming. This paper presents a novel, automated concrete surface defects detection and assessment approach that addresses these issues by automatically quantifying the extent of surface deterioration. According to this approach, images of the surface shot from a certain angle/distance can be used to automatically detect the number and size of surface air pockets, and the degree of surface discoloration. The proposed method uses histogram equalization and filtering to extract such defects and identify their properties (e.g. size, shape, location). These properties are used to quantify the degree of impact on the concrete surface quality and provide a numerical tool to help inspectors accurately evaluate concrete surfaces. The method has been implemented in C++ and results that validate its performance are presented.

Augmented attribute representations

We propose a new learning method to infer a mid-level feature representation that combines the advantage of semantic attribute representations with the higher expressive power of non-semantic features. The idea lies in augmenting an existing attribute-based representation with additional dimensions for which an autoencoder model is coupled with a large-margin principle. This construction allows a smooth transition between the zero-shot regime with no training example, the unsupervised regime with training examples but without class labels, and the supervised regime with training examples and with class labels. The resulting optimization problem can be solved efficiently, because several of the necessity steps have closed-form solutions. Through extensive experiments we show that the augmented representation achieves better results in terms of object categorization accuracy than the semantic representation alone. © 2012 Springer-Verlag.

Positive Correlations in Tunneling through coupled Quantum Dots

Due to the Fermi-Dirac statistics of electrons the temporal correlations of tunneling events in a double barrier setup are typically negative. Here, we investigate the shot noise behavior of a system of two capacitively coupled quantum dot states by means of a Master equation model. In an asymmetric setup positive correlations in the tunneling current can arise due to the bunching of tunneling events. The underlying mechanism will be discussed in detail in terms of the current-current correlation function and the frequency-dependent Fano factor.

Synchronization of user-generated videos through trajectory correspondence and a refinement procedure

Temporal synchronization of multiple video recordings of the same dynamic event is a critical task in many computer vision applications e.g. novel view synthesis and 3D reconstruction. Typically this information is implied through the time-stamp information embedded in the video streams. User-generated videos shot using consumer grade equipment do not contain this information; hence, there is a need to temporally synchronize signals using the visual information itself. Previous work in this area has either assumed good quality data with relatively simple dynamic content or the availability of precise camera geometry. Our first contribution is a synchronization technique which tries to establish correspondence between feature trajectories across views in a novel way, and specifically targets the kind of complex content found in consumer generated sports recordings, without assuming precise knowledge of fundamental matrices or homographies. We evaluate performance using a number of real video recordings and show that our method is able to synchronize to within 1 sec, which is significantly better than previous approaches. Our second contribution is a robust and unsupervised view-invariant activity recognition descriptor that exploits recurrence plot theory on spatial tiles. The descriptor is individually shown to better characterize the activities from different views under occlusions than state-of-the-art approaches. We combine this descriptor with our proposed synchronization method and show that it can further refine the synchronization index. © 2013 ACM.

Semantic transform: Weakly supervised semantic inference for relating visual attributes

Relative (comparative) attributes are promising for thematic ranking of visual entities, which also aids in recognition tasks. However, attribute rank learning often requires a substantial amount of relational supervision, which is highly tedious, and apparently impractical for real-world applications. In this paper, we introduce the Semantic Transform, which under minimal supervision, adaptively finds a semantic feature space along with a class ordering that is related in the best possible way. Such a semantic space is found for every attribute category. To relate the classes under weak supervision, the class ordering needs to be refined according to a cost function in an iterative procedure. This problem is ideally NP-hard, and we thus propose a constrained search tree formulation for the same. Driven by the adaptive semantic feature space representation, our model achieves the best results to date for all of the tasks of relative, absolute and zero-shot classification on two popular datasets. © 2013 IEEE.

Spin-dependent current noises in transport through coupled quantum dots

Current fluctuations can provide additional insight into quantum transport in mesoscopic systems. The present work is carried out for the fluctuation properties of transport through a pair of coupled quantum dots which are connected with ferromagnetic electrodes. Based on an efficient particle-number-resolved master equation approach, we are concerned with not only fluctuations of the total charge and spin currents, but also of each individual spin-dependent component. As a result of competition among the spin polarization, Coulomb interaction, and dot-dot tunnel coupling, rich behaviors are found for the self- and mutual-correlation functions of the spin-dependent currents.

A new way of uniform splitting of the optical power by directional coupling between the photonic crystal waveguides

Directional coupler can be constructed by putting multiple photonic crystal waveguides together. The propagation of the optical field entering this system symmetrically was analysed numerically according to self-imaging principle. On the basis of this structure, ultracompact multiway beam splitter was designed and the ones with three and four output channels were discussed in details as examples. By simply tuning the effective refractive index of two dielectric rods in the coupler symmetrically to induce the redistribution of the power of the optical field, uniform or free splitting can be achieved. Compared with the reported results, this way is simpler, more feasible and more efficient and has extensive practical value in future photonic integrated circuits.

Full counting statistics of transport through two-channel Coulomb blockade systems

A mesoscopic Coulomb blockade system with two transport channels is studied in terms of full counting statistics. It is found that the shot noise and skewness are crucially affected by the quantum mechanical interference. In particular, the super-Poisson behavior can be induced as a consequence of constructive interference, and can be understood by the formation of effective fast-and-slow transport channels. Dephasing and finite temperature effects are carried out together with physical interpretations.

Calculation of the current noise spectrum in mesoscopic transport: A quantum master equation approach

Based on our recent work on quantum transport [X. Q. Li , Phys. Rev. B 71, 205304 (2005)], we show how an efficient calculation can be performed for the current noise spectrum. Compared to the classical rate equation or the quantum trajectory method, the proposed approach is capable of tackling both the many-body Coulomb interaction and quantum coherence on an equal footing. The practical applications are illustrated by transport through quantum dots. We find that this alternative approach is in a certain sense simpler and more straightforward than the well-known Landauer-Buttiker scattering matrix theory.

Partially coherent tunneling through a series of barriers: Inelastic scattering versus pure dephasing

Within the Buttiker dephasing model, the backscattering in the dephasing process is eliminated by setting a proper boundary condition. Explicit expression is carried out for the effective total tunneling probability in the presence of multiple pure dephasing scatterers with partial coherence. The derived formula is illustrated analytically by various limiting cases, and numerically for its application in tunneling through multibarrier systems.

ELECTRONIC-STRUCTURES OF THE ALKALI-CONTAINING BUCKMINSTERFULLERENES (A-DELTA-C60) (A=LI,NA,K,RB,CS) AND THE HALOGEN-CONTAINING BUCKMINSTERFULLERENES (H-DELTA-C60) (H=F,CL,BR,I)

The geometrical parameters and electronic structures of C60, (A partial derivative C60) (A = Li, Na, K, Rb, Cs) and (H partial derivative C60) (H = F, Cl, Br, I) have been calculated by the EHMO/ASED (atom superposition and electron delocalization) method. When putting a central atom into the C60 cage, the frontier and subfrontier orbitals of (A partial derivative C60) (A = Li, Na, K, Rb, Cs) and (H partial derivative C60) (H = F, Cl) relative to those of C60 undergo little change and thus, from the viewpoint of charge transfer, A (A = Li, Na, K, Rb, Cs) and H (H = F, Cl) are simply electron donors and acceptors for the C60 cage resPeCtively. Br is an electron acceptor but it does influence the frontier and subfrontier MOs for the C60 cage, and although there is no charge transfer between I and the C60 cage, the frontier and subfrontier MOs for the C60 cage are obviously influenced by I. The stabilities DELTAE(X) (DELTAE(X) = (E(X) + E(C60)) - E(x partial derivative C60)) follow the sequence I < Br < None < Cl < F < Li < Na < K < Rb < Cs while the cage radii r follow the inverse sequence. The stability order and the cage radii order have been explained by means of the (exp-6-1) potential.

Smaller Ge Quantum Dots Obtained by ArF Excimer Laser Annealing

Ge self-assembled quantum dots (SAQDs) are grown with a self-assembled UHV/CVD epitaxy system. Then,the as-grown Ge quantum dots are annealed by ArF excimer laser. In the ultra-shot laser pulse duration,～20ns, bulk diffusion is forbidden, and only surface diffusion occurs, resulting in a laser induced quantum dot (LIQD). The diameter of the LIQD is 20～25nm which is much smaller than the as-grown dot and the LIQD has a higher density of about 6 × 10~(10)cm~(-2). The surface morphology evolution is investigated by AFM.

Electron trapping materials for use in a picosecond infrared streak camera

We describe our research on the employment of an infrared upconversion screen made of electron trapping material (ETM) in combination with the high sensitivity of the S-20 photocathode responsive to visible radiation to produce a streak camera arrangement capable of viewing and recording infrared incident pulses. The ETM-based upconversion screen converts 800-1600 nm infrared radiation to visible light which is viewed or recorded by the S-20 photocathode. The peak values of the upconversion efficiency are located at 1165 nm for CaS:Eu, Sm and 1060 nm for CaS:Ce, Sm. The present experiment showed time resolution was 12.3 ps for a CaS:Eu, Sm screen and 8.4 ps for a CaS:Ce, Sm screen. The minimum detectability is 4.8 x 10(-9) J/mm(2) (minimum detectability of the coupled visible streak camera is 8.3x10(-10) J/mm(2)). Other parameters, such as spatial resolution and dynamic range, have also been measured and analyzed. The results show ETM can be used in the measurement of infrared ultrafast phenomena up to picosecond time domain. In consideration of the limited number of trapped electrons in ETM, the infrared-sensitive streak camera consisting of an ETM-based upconversion screen is suitable to operate in the single shot mode. (C) 1999 American Institute of Physics. [S0034-6748(99)00112-4].

2-D and 3-D processing and interpretation of multi-fold ground penetrating radar data:a case history from an archaeological site

A 2.5-D and 3-D multi-fold GPR survey was carried out in the Archaeological Park of Aquileia (northern Italy). The primary objective of the study was the identification of targets of potential archaeological interest in an area designated by local archaeological authorities. The second geophysical objective was to test 2-D and 3-D multi-fold methods and to study localised targets of unknown shape and dimensions in hostile soil conditions. Several portions of the acquisition grid were processed in common offset (CO), common shot (CSG) and common mid point (CMP) geometry. An 8×8 m area was studied with orthogonal CMPs thus achieving a 3-D subsurface coverage with azimuthal range limited to two normal components. Coherent noise components were identified in the pre-stack domain and removed by means of FK filtering of CMP records. Stack velocities were obtained from conventional velocity analysis and azimuthal velocity analysis of 3-D pre-stack gathers. Two major discontinuities were identified in the area of study. The deeper one most probably coincides with the paleosol at the base of the layer associated with activities of man in the area in the last 2500 years. This interpretation is in agreement with the results obtained from nearby cores and excavations. The shallow discontinuity is observed in a part of the investigated area and it shows local interruptions with a linear distribution on the grid. Such interruptions may correspond to buried targets of archaeological interest. The prominent enhancement of the subsurface images obtained by means of multi-fold techniques, compared with the relatively poor quality of the conventional single-fold georadar sections, indicates that multi-fold methods are well suited for the application to high resolution studies in archaeology.

A conceptual approach to integrated coastal management

This paper focuses on the concept of Integrated Coastal Management (ICM) putting the theoretical basis of Chapter 17, Agenda 21 (UN Conference on Environment and Development, UNCED), in relation to the theoretical backgrounds on which the development of coastal area programmes have been founded. Reasoning leads us to think that the general system theory is the proper conceptual basis to stimulate ICM and that, in this theoretical context, integration is to be pursued between (i) the claiming of national maritime jurisdictional belts and the protection of the coastal ecosystem, (ii) the coastal system and its external environment, (iii) the decision making systems acting at all levels (international, regional, national and local). Integration, therefore, should be thought of as a political process.