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The structure of basic lanthanum orotate (LaOr) were characterized by elemental analysis and infrared spectroscopy. The thermal stability of polyvinyl chloride (PVC) was further studied by Congo red method, oven discoloration method and thermogravimetric analysis. The results showed that LaOr could prolong the oven discoloration time of PVC, and the color was not completely blackened until 120 min. It has a good synergetic effect with dibenzoyl methane (DBM), and the best effect is achieved when LaOr/DBM ratio is 1.8/1.2. The thermal decomposition kinetics experiment showed that adding DBM can effectively improve the activation energy of PVC/LaOr. The stabilization mechanism of PVC was studied by absorbing HCl method and infrared spectroscopy. The results showed that LaOr could not only replace the unstable chlorine atoms on PVC, but also promote the long-term thermal stability of PVC by absorbing HCl.

The Paleoproterozoic Jiao-Liao-Ji Orogenic Belt is a part of the Eastern Block, North China Craton. The Shuangcha rock mass has been recently recognized in Laohe group of Jiao-Liao-Ji Orogenic Belt, and it consists of mainly porphyritic monzonitic granite and porphyritic K-feldspar granite. We present detailed studies of petrography, geochronology and geochemistry of Shuangcha rock mass to constrain the petrogenesis and tectonic evolution features of the Jiao-Liao-Ji Orogenic Belt. The mineral of the Shuangcha granite consists of K-feldspar, plagioclase, quartz and a small amount of biotite ( 350 ppm) and 10,000Ga/Al ratios (average 2.69), which are typical features of A-type granite. The Shuangcha A-type granites can be further subdivided into A2-type subgroup based on some geochemical features, such as high Y/Nb ratios (0.99~3.14, average 1.84). Petrographic and geochemical studies have shown that the Shuangcha granites were the product of partial melting of quartzo-feldspathic rocks under a high temperature (>899°C), low pressure and anhydrous environment. Based on geochemical studies of Shuangcha granites, spatial and temporal distributions of regional magmatism and metamorphism records, the Jiao-Liao-Ji Orogenic Belt was in a typical post-collision extension setting in late Paleoproterozoic period (1.82~1.88 Ga) probably triggered by the slab breaks off.

New petrological, whole-rock geochemical, zircon U–Pb geochronological, and zircon Lu–Hf isotopic data have been reported for Early Cretaceous intrusive rocks in the Wulong region of the Liaodong Peninsula on the North China Craton. The zircon U-Pb chronology shows that the crystallization age of six groups of intrusive rocks from this region is 129–123 Myr ago. These intrusive rocks can be categorized into A-type granite (granodiorite), K-rich adakite (porphyritic-like monzogranite), highly fractionated I-type granites (porphyritic-like biotite monzogranite, porphyritic-like syenogranite, and syenogranite), and gabbro. These granitoids are shown to have negative zircon eHf(t) values(-21.0 to -11.1) with old two-stage Hf model ages (TDM2(Hf)) (1.88–2.50 Ga), while gabbro has higher zircon eHf(t) values(-14.3 to -9.4) with younger TDM2(Hf) (1.77–2.08 Ga) model ages. According to our results, we believe that the porphyritic-like monzogranite was produced through partial melting of the thickened eclogitic lower crust, the gabbro was generated by partial melting of a source formed by the mixing of enriched lithospheric mantle and delaminated eclogitic lower crust, the granodiorite was formed by mixing crust materials and mafic melts, the porphyritic-like biotite monzogranite, porphyritic-like syenogranite, and syenogranite originated from the medium- to high-K basaltic lower crust. The bimodal intrusive rocks (gabbro, porphyritic-like monzogranite, and porphyritic-like biotite monzogranite) and A-type granites (granodiorite) were emplaced in an extensional setting associated with Paleo-Pacific Plate subduction. We also determined that the tectonic setting changed from extension to transpression during 125–120 Myr ago (porphyritic-like syenogranite and syenogranite). Moreover, we confirmed the hypothesis that the Early Cretaceous delamination is the result of Paleo-Pacific Plate subduction.

The tectonic setting of Jurassic magmatism in the Northeast China (NE China) is unclear. Here, we present new petrological, whole-rock geochemical, zircon U-Pb geochronological, and zircon Lu-Hf isotope data for Jurassic granitoids of the Wulong region, Liaodong Peninsula, NE China. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U-Pb data indicate that these granitoids were emplaced at 165–156 Ma. The biotite monzogranite, two-mica monzogranite, monzogranite, granodiorite, biotite granodiorite, and syenogranite are strongly peraluminous (A/CNK=1.09–1.29), contain peraluminous minerals such as muscovite, have high normative corundum abundances (1.26 wt.%–3.28 wt.%), and have high K2O/Na2O ratios (0.76–1.48), all of which indicate an S-type granite affinity. However, the biotite granodiorite and syenogranite have high Sr (391 ppm–570 ppm) and low Y (3.06 ppm–5.94 ppm) contents, with high Sr/Y (65.8–185.9) ratios, and the two-mica monzogranite, monzogranite, and granodiorite have relatively high Sr (138 ppm–379 ppm) and low Y (3.38 ppm–8.71 ppm) contents, with high Sr/Y ratios (19.1–77.9). All of the analyzed samples have negative zircon eHf(t) values (−41.4 to −20.6) with old two-stage Hf model ages (TDM2(Hf)=2.50–3.76 Ga). Therefore, we infer that the biotite monzogranite is the typical feature of S-type granite that was derived by partial melting of metagraywacke. The monzogranite, two-mica monzogranite, granodiorite, biotite granodiorite, and syenogranite exhibit geochemical characteristics of S-type granite with K-rich adakitic features, and were possibly derived by mixing of melts from clastic crustal materials and adakitic magmas. There are voluminous Jurassic igneous rocks in the NE China. By combining our study with the previous researches, this paper infers that the Jurassic magmatism within the Erguna-Xing’an Massif was related to the southward subduction and closure of the Mongol-Okhotsk Ocean; the Early Jurassic magmatism to the east of the Songliao Basin and in the northern North China Craton (NCC) was related to the subduction of the Pacific Plate; however, the Middle-Late Jurassic igneous rocks to the west of the Songliao Basin were related to the closure of the Mongol-Okhotsk Ocean and, in the northern NCC, were related to closure of the Mongol-Okhotsk Ocean with an influence from flat-slab subduction of the Pacific Plate.

The Xiarihamu Cu–Ni sulfide deposit is the second-largest Cu–Ni deposit in China, located in the Eastern Kunlun orogenic belt. However, despite previous study, the formation and evolution of this deposit remains a key unknown in the tectonic evolution of the Eastern Kunlun Orogenic Belt. Moreover, the petrogenesis of the ore-bearing rocks and the nature of ore genesis are the subjects of ongoing debate. Here, we present detailed field observations, petrology, zircon U–Pb geochronology, and Re–Os isotopic analyses to constrain the timing and genesis of the Xiarihamu Cu–Ni sulfide deposit. Sulfides from the massive ores yielded a Re–Os isotopic isochron age of 408 ± 11 Ma. Four samples from the ore-bearing Xiarihamu mafic–ultramafic intrusions yielded zircon U–Pb ages of 423.1 ± 2 Ma, 422.9 ± 3.1 Ma, 422.7 ± 2.3 Ma, and 422.6 ± 2.7 Ma, respectively, indicating that the ore formed during the Silurian. The calculated initial 187Os/188Os ratio and γOs values ranged from 0.5109 to 0.8499 and from 311 to 584, respectively, indicating that crustal contamination played an extremely important role in triggering sulfide saturation. In combination with previous research, drill core observations and Re–Os data provide robust evidence for multiple pulses of magma replenishment throughout the process of ore genesis. Based on this evidence, the large-scale magmatic Cu–Ni mineralization in Xiarihamu likely occurred in a post-collisional setting related to tectonic slab breakoff.

Triassic granitic magmatism is widespread in the Eastern Kunlun Orogenic Belt (EKOB), northern Tibetan Plateau. Some of the granitoids are characterized by high Sr and low Y contents, and consequently high Sr/Y ratios. These high Sr/Y-ratio granitoids are often interpreted as adakitic rocks, originating from the thickened continental lower crust. However, studies have shown that granitoids with high Sr/Y ratios may have formed via other geological processes. This paper reports U–Pb ages, geochemical and Sr–Nd–Hf isotopic data for newly discovered granodiorite porphyries in the Kunlun River area of the Eastern Kunlun Orogenic Belt, and discusses whether the EKOB experienced crustal thickening during the Triassic. The granodiorite porphyries crystallized at 205 Ma. They have some adakitic characteristics with SiO2 = 66.96–69.68 wt.%, Sr/Y ratios = 31–43, La/Yb = 26.9–57.9, Y = 8.47–11.3, Yb = 0.75–1.30, and MgO = 0.44–0.99 wt.%. However, the relatively flat heavy rare earth element patterns indicate that garnet was not the main residue in the magma source. In addition, combined with Nd–Hf isotopic data, these results indicate that the timing of the original generation of the crustal sources of the granodiorites should be Mesoproterozoic, with the involvement of older (Paleoproterozoic) components. The granodiorite porphyries were emplaced in a post-collisional environment after the northward subduction of Paleo-Tethyan oceanic lithosphere, and without thickening of the continental crust.

The Zhanbuzhale region, in the Eastern Kunlun Orogen of northwestern China, is characterized by large volumes of Phanerozoic granitoid rocks and is an ideal region for investigating the tectonic evolution of the Paleo-Tethys system. However, the exact timing of the final closure of the Paleo-Tethys Ocean and initial continental collision remains controversial because of a lack of precise geochronological and detailed geochemical data. In this paper, we report new zircon U–Pb ages and mineralogical, petrographic, and geochemical data for samples of Middle Triassic granodiorite and alkali feldspar granite from the Zhanbuzhale region. The zircon U–Pb ages indicate that the granodiorite and alkali feldspar granite formed at 239 and 236 Ma, respectively. The granodiorites are high-K calc-alkaline, metaluminous, high Sr content, high Sr/Y ratios, low Y content, and show adakite-like affinities. The alkali feldspar granites display high SiO2, extremely low MgO, and low Zr+Nb+Ce+Y contents as well as low Fe2O3t/MgO ratios, showing metaluminous to peraluminous and high-K calc-alkaline features. Geochemical and petrological characteristics of the alkali feldspar granites suggest that they are highly fractionated I-type granites. The granodiorites and alkali feldspar granites have zircon εHf(t) values ranging from –2.26 to –0.18, and from –2.17 to +2.18, respectively. Together with regional geological data, we propose that the Triassic (approximately 239–236 Ma) granitoids were generated during the later stages of northward subduction of the Paleo-Tethys oceanic plate, and that the initial stage of collision between the East Kunlun and the Bayan Har–Songpan Ganzi terrane occurred at approximately 236–227 Ma.

3D printing is a novel construction method, which utilizes sequential deposition of printable material to build structures. It contributes to the automation in civil engineering and offers advantages of design, greenness and efficiency. Similarities between conventional spray technology and 3D printing indicate the feasibility of spray-based 3D printing, which could enhance the automation in vertical and overhead construction. However, low dimensional accuracy of sprayed profiles with conventional materials greatly affects the quality of spray-based 3D printing. This study contributes to the development of cementitious material to improve the dimensional accuracy of spray-based 3D printing. In this study, fly ash cenosphere and air entraining agent were introduced to obtain the optimal mixture design considering the delivery and deposition requirements. Subsequent spray tests show that the optimal mixture has the smallest splash width and most uniform material distribution among all the designed mixtures. Analysis of deposition process reveals that the distribution of sprayed material is closely related with its rheological properties, which could guide the future research work on spray-based printing of cementitious materials. Accepted version

3D printing, or additive manufacturing, is a technology which adopts layer-by-layer additive deposition process to build three-dimensional objects. Over the past decade, 3D printing has been attracting more and more attention in the building and construction industry. Compared with conventional concrete casting techniques, 3D printing contributes to higher efficiency with freeform construction, greatly reduced labor and much less construction waste. However, 3D printable cementitious materials are different from conventional concrete in terms of rheology, printability, and mechanical performances. This paper aims to systematically bridge the gap between the requirement and research and development of 3D printable cementitious materials to date. Guided by 3D printing process and multi-level design of cementitious materials, the requirements for 3D printable cementitious material at different material development levels are discussed. This paper provides insights for the future development of 3D printable cementitious materials for building and construction by controlling the basic inputs of materials to obtain desired structural performance. Accepted version

The disposal of post-consumer glass has been a major issue due to its inert properties that may cause environmental effects, while recycling of these glasses is only feasible if the waste glass recovered is sorted into its different colour to prevent chemical incompatibility in the manufacturing process. 3D printing in building and construction has gain increasing attention in the past decade and provides a potential to sustainably utilize the recycled unsorted glasses. This paper examines the use of recycled glass as the fine aggregates for 3D concrete printing applications. Despite the several studies done on the use of recycled glass in concrete, there is a lack of focus on the rheology of the material which is essential to the performance of the material in 3D concrete printing. Although results have shown that the mechanical strength for the recycled glass concrete is lower than the sand aggregates concrete, yet the flow properties of the former is better than the latter. Nonetheless, a balance between the mechanical strength and flowability of the mix design should be studied. The future work revolves around the optimization of the mix design using a combination of sand and recycled glass, adjusting the gradation of recycled glass particles and addition of accelerators to improve its buildability and mechanical strengths. Accepted version

Scene text in the video is usually vulnerable to various blurs like those caused by camera or text motions, which brings additional difficulty to reliably extract them from the video for content-based video applications. In this paper, we propose a novel fully convolutional deep neural network for deblurring and detecting text in the video. Specifically, to cope with blur of video text, we propose an effective deblurring subnetwork that is composed of multi-level convolutional blocks with both cross-block (long) and within-block (short) skip connections for progressively learning residual deblurred image details as well as a spatial attention mechanism to pay more attention on blurred regions, which generates the sharper image for current frame by fusing multiple surrounding adjacent frames. To further localize text in the frames, we enhance the EAST text detection model by introducing deformable convolution layers and deconvolution layers, which better capture widely varied appearances of video text. Experiments on the public scene text video dataset demonstrate the state-of-the-art performance of the proposed video text deblurring and detection model.

In this paper, an integrated circuit (IC) solder joint inspection algorithm is proposed based on an adaptive-template method. To the best of our knowledge, it is the first time to utilize the adaptive-template scheme for IC solder joint inspection. First, a number of qualified solder joint images are used to construct a dictionary. Then, we formulate the construction of the adaptive template for each IC solder joint as an optimization problem, which is solved by the elastic net. The defects can be inspected by the difference image between the IC solder joint image and its corresponding adaptive template. We propose a weighting scheme to highlight the defects in the solder joint images, in which different weights are given to different pixel locations in the difference images. Finally, the weighted defect score is defined to evaluate the quality of the solder joint image. Experimental results indicate that the proposed method is superior to the existing methods in terms of omission rate and error rate.

Linear models are commonly used to describe the early structural build-up of cement-based materials. However, some studies have shown that there exists a faster non-linear phase before the linear phase. In this study, a simple non-linear thixotropy model is presented to describe the structural build-up process. It was quantified using static yield stress and storage modulus, which are measured through the stress growth protocol and small amplitude oscillatory shear (SAOS) tests, respectively. The effect of pre-shear, rest condition and viscosity modifying admixtures (nanoclay and diutan gum) on the build-up behavior are studied. The results showed distinctly different trends between static yield stress and storage modulus. This may be attributed to the two different structures of fresh cement pastes, i.e. floc structures and C-S-H structures, measured by the stress growth protocol and SAOS test, respectively.

Electrocardiogram (ECG) signal denoising is an important preprocessing for ECG signal analysis. The contaminated ECG signal can be considered as the combination of the desired clean signal and the noise. Thus, ECG signal denoising can be considered as a problem of obtaining an optimal solution to the desired clean signal. In this paper, an effective optimization scheme for ECG signal denoising is presented based on low-rank matrix decomposition. First, the ECG denoising problem is formulated as low-rank matrix decomposition. So, an ECG beats matrix is assumed to be the combination of a sparse noise matrix and a low-rank matrix. Considering the repeatability of ECG signal, the rank of the ECG beats matrix is assumed to be one. Then, to fully exploit the low-rank property of the ECG signal, the matrix decomposition is modified by means of adding different weights to different singular values. Finally, the desired clean ECG signal is reconstructed by the low-rank component. The experimental results show that the proposed denoising method achieves the best performance of suppressing the electromyographic noise in the ECG signals compared with other optimization models.

In this performance-based study, the effect of palygorskite clays and carbon nanotubes (CNTs) on the rheological and hardened properties of a cement mortar and a blended mortar containing cement, fly ash and blast furnace slag were compared. Results showed that although the control cement mortar and control blended mortar exhibited similar rheological parameters, the additives had differing effects on each system. Palygorskite clays increased yield stress and static cohesion and decreased plastic viscosity in both systems but these effects were more marked in the cement mortar than in the blended. On the other hand, CNTs increased all measured rheological parameters in the cement mortar and decreased them in the blended. The rheological results highlighted the importance of considering the binder system when utilizing additives with exceptional surface properties like CNTs and palygorskite clays. In the hardened state, electrical resistivity, compressive strength, and tensile strength were evaluated. Results indicated that although the palygorskite clays are utilized primarily as a rheological modifier, they can also enhance mechanical properties.

During steel strip production, mechanical forces and environmental factors cause surface defects of the steel strip. Therefore, detection of such defects is key to the production of high quality products. Moreover, surface defects of the steel strip cause great economic losses to the high-tech industry. So far, few studies have explored methods of identifying the defects, and most of the currently available algorithms are not sufficiently effective. Therefore, we developed an end-to-end defect detection model based on YOLO-V3. Briefly, the anchor-free feature selection mechanism was utilized to select an ideal feature scale for model training, replace the anchor-based structure, and shorten the computing time. Next, specially designed dense convolution blocks were introduced into the model to extract rich feature information, which effectively improves feature reuse, feature propagation, and enhances the characterization ability of the network. The experimental results show that, compared with other comparison models, the improved model proposed in this study has higher performance. For instance, the proposed model yielded 71.3% mAP on the GC10-DET dataset, and 72.2% mAP on the NEU-DET dataset.

The Wuxing deposit in Northeast China, tectonically located in the Jiamusi–Khanka Block, is a Pt–Pd-rich Cu-Ni sulfide deposit related to mafic–ultramafic rocks. The zircon U–Pb ages of pyroxenites , gabbros , porphyritic granites , and leucogranits in the mining area are 516.7 ± 2.6, 513.8 ± 2.0, 505.4 ± 2.3 and 499.5 ± 2.9 Ma, respectively, indicating that the diagenesis and metallogenesis of the Wuxing deposit occurred during the Cambrian. The ore-forming complex is cut by quartz diorite porphyritic and plagiogranite porphyry dikes. Zircon U–Pb ages of the quartz diorite porphyrite and plagiogranite porphyry are 206.6 ± 2.1 and 201.6 ± 1.3 Ma, respectively. The U–Pb ages indicate the metallogenic age constraint of 516.7 ± 2.6 Ma for the Wuxing deposit, rather than Cambrian and Triassic magmatic activities. The Hf isotopic composition e Hf(t) of zircons in the pyroxenites and gabbros are −11.5 to −7.7 and −5.8 to −2.5, with the two–stage model ages (tDM2 ) of 2198–1958 and 1841–1633 Ma, respectively. Geochemically, the mafic–ultramafic complexes are enriched in light rare earth elements (LREE) and large ion lithophile elements (LILE), and depleted in high-field strength elements (HFSE), indicating these rocks originated from the enriched mantle. The porphyritic granites are high-K calc-alkaline rocks (Rittman index δ = 1.92–2.00), and the leucogranites are low-K alkaline rocks ( δ = 4.76–4.86) with eHf(t) and tDM2 of −9.2 to +0.8 and 2037–1411 Ma, respectively. The porphyritic granites and leucogranites are characterized by low A/CNK values (0.91–1.05), 10,000 Ga/Al values (1.76–2.36), and Zr saturation temperature (731–823 ℃) similar to those of I-type granites. Along with contemporaneous intrusions, the Wuxing deposit is inferred to have formed in a post-collisional extension environment. Consequently, the origin of the Wuxing deposit is likely related to the evolution of enriched mantle magma during the Cambrian post-collision extensional setting of the Jiamusi–Khanka Block.

Water reducing agents including polycarboxylate ether superplasticizer (PCE) have been found to have retardation effect on hydration heat and setting of cementitious materials, which is a long term effect after 8 h. However, the short term effect within 3 h of PCE on workability and workability loss, which could result in failure during SCC pumping or continuous concrete 3D printing, is not clear. This study explores the effects of PCE on flowability and structural build-up of cement pastes in fresh states using rheometer. Strength and modulus, such as the dynamic and static yield stress, and storage modulus are measured over time up to 2.5 h. They are measured by step down protocol, stress development protocol (i.e. low constant shear rate test), and small amplitude oscillatory sweep, respectively. Plastic viscosity fitted in Bingham model and critical strain using oscillatory test are also recorded. The effect of dosage of PCE addition and time are studied. It is found that in both cases where w/c are 0.3 and 0.4, low dosage of PCE addition exhibits much higher increasing rates of structural build-up than plain cement paste or at high dosage of PCE addition. It highlights attention needed on structural build-up at fresh state with low dosage of PCE addition. Possible mechanisms, especially effect of PCE polymers on colloidal flocculation and early hydrates formation, are also discussed and reasoned.

The sparsity adaptive matching pursuit (SAMP) algorithm has an advantage of reconstructing signals without the prior information of the sparsity level. However, the required computational power is high and the reconstruction performance is not satisfied for perturbed systems. This is because this algorithm is based on the expectation maximization algorithm. Also, a pseudo-inverse operation of the matrix is employed to select the element candidates of the sensing matrix in each iteration. In this paper, a mixed $$L_{1}$$ norm and $$L_{2}$$ norm regularized algorithm is proposed to address these issues. Similar to the SAMP algorithm, the regularized algorithm also reconstructs the signals without the prior information of the sparsity level. Different from the SAMP algorithm, the element candidates of the sensing matrix are selected by the $$L_{2}$$ norm strategy in each iteration. Experiments are performed on an ideal simulation system, a perturbed simulation system and real image reconstruction. Simulation and real image reconstruction experimental results indicate that the regularized algorithm has lower computational power than the SAMP algorithm. Also, the proposed algorithm has better reconstruction performance on the perturbed system compared to the SAMP algorithm.

To improve the measurement accuracy of an absolute imaging position encoder, a novel edge detection method is developed to accurately detect the edges of grating lines based on empirical mode decomposition (EMD). First, according to the characteristics of the absolute position coding image (APCI), the vertical projection of the grey-level APCI is achieved by conventional grey-level transformation. Then, the vertical projection contour is decomposed by an EMD method and a finite number of intrinsic mode functions (IMFs) are achieved. Next, the last two IMFs are used to describe the trend of the projection contour. The trend is used as adaptive thresholds to divide the vertical projection contour into different intervals. Finally, the second derivate of the vertical projection contour is applied to obtain the accurate edges in each interval. Experimental results indicate that the proposed method is more robust to heavy noise, bad illumination and a slope compared with the existing methods with respect to edge detection. Also, the proposed method achieves better measurement accuracy than the existing methods.

Defect inspection of integrated circuits (ICs) solder joints is a long-standing task. This paper proposes a novel IC solder joint inspection method based on the idea of robust principle component analysis (RPCA), which is a celebrated optimization technique. To the best of our knowledge, this is the first time IC solder joint inspection is formulated as an optimization problem. In particular, we model an IC solder joint image as observed data corrupted by gross errors. According to the RPCA theory, the observed data can be approximately decomposed into a low-rank component and an error component. In this paper, an appearance model of qualified IC solder joints is defined for IC solder joint inspection based on RPCA. Then, a defect score is defined based on the appearance model and is used to evaluate the quality of IC solder joints. Meanwhile, location prior knowledge related to human perception is incorporated in the defect score to further evaluate the defects of IC solder joints. Finally, a simple discrimination scheme is proposed to inspect IC solder joints. Experimental results indicate that the proposed method is superior to the existing methods in inspection performance.

In this study, a creep recovery shear rheological protocol was applied to fresh cement pastes. A viscosity bifurcation behavior was observed through applying a range of creep stresses. When applied stress is sufficiently low viscosity increases and the material yields, exhibiting viscoelastic solid-like behavior. Beyond a critical stress viscosity decreases and the material flows, exhibiting viscoelastic liquid-like behavior. Through examining this bifurcation behavior we found that the transition of viscosity occurs at very low strains. The strains at which this transition occurred were compared with critical strains measured through low amplitude oscillatory shear. Results provided support that the solid-liquid transition occurs beyond the critical stress measured through creep, thereby tying it to static yield stress. The protocol was implemented to probe pastes modified with attapulgite clays, a highly thixotropic system, and was found to be effective in characterizing static yield stress and thixotropic rebuilding.

We propose an automatic parametric human body reconstruction algorithm which can efficiently construct a model using a single Kinect sensor. A user needs to stand still in front of the sensor for a couple of seconds to measure the range data. The user's body shape and pose will then be automatically constructed in several seconds. Traditional methods optimize dense correspondences between range data and meshes. In contrast, our proposed scheme relies on sparse key points for the reconstruction. It employs regression to find the corresponding key points between the scanned range data and some annotated training data. We design two kinds of feature descriptors as well as corresponding regression stages to make the regression robust and accurate. Our scheme follows with dense refinement where a pre-factorization method is applied to improve the computational efficiency. Compared with other methods, our scheme achieves similar reconstruction accuracy but significantly reduces runtime.

Text in natural scene images are often faced with low-resolution problem, which brings significant difficulties to many text-related tasks such as text detection and recognition. In this paper, we propose a novel text-attentional Conditional Generative Adversarial Network (cGAN) model for text image super-resolution (SR). The model enhances the original cGAN by introducing effective channel and spatial attention mechanisms based on the proposed Residual Dense Channel Attention Block and text/non-text segmentation information, which focus the model on the text regions instead of the background of the image to learn more effective representations of text and achieve better text super-resolution result. The proposed model achieves state-of-the-art performances on public text image super-resolution dataset.

Rheological studies are important for successful 3D concrete printing. The main challenge for successful 3D concrete printing is the complex characteristic the materials should possess. It should be flowable enough to be pumped and extruded through the hose, as well as gaining sufficient strength and stiffness for buildability after the layer by layer deposition. Existing literature has various mixtures proposed for successful 3D concrete printing. Most of these studies used rheometers to measure the dynamic yield stress and plastic viscosity. As the measurement with rheometer is sensitive to the protocols and is controlled by the rheologists, as well as data processing if non-standardized measuring geometries are used, results could vary significantly. This study used standardized field-friendly protocols to measure the slump and slump-flow of the mortars. The pumpability and buildability are evaluated in terms of the pumpability index and maximum height printed before collapsing. These result together with the slump and slump-flow values are used to define the printable region. Accepted version

Purpose This paper aims to inspect solder joint defects of integrated circuit (IC) components on printed circuit boards. Here, an IC solder joint inspection algorithm is developed based on a Gaussian mixture model (GMM). Design/methodology/approach First, the authors train a GMM using numerous qualified IC solder joints. Then, the authors compare the IC solder joint images with the trained model to inspect the potential defects. Finally, the authors introduce a frequency map and define a metric termed as normalized defect degree to evaluate qualities of the tested IC solder joints. Findings Experimental results indicate that the proposed method is superior to the state-of-the-art methods on IC solder joint inspection. Originality/value The approach is a promising method for IC solder joint inspection, which is quite different from the traditional classifier-based methods.

Freeze-thaw cycle is one of the major damage factors of concrete patch repair. Not only the material itself but also the adhesive interface is damaged under freeze-thaw cycles (FTC). Air-entraining agent has long been used to increase the freeze-thaw resistance of concrete materials. However, the effect of air-entraining agent on the adhesive interface has not been explored. The degradation mechanism and failure mode of concrete repair system under FTC has not been studied, either. In this study, three kinds of substrate concrete were casted and repaired by two kinds of ordinary Portland cement mortars and one kind of polymer-modified cement mortar (PCM), respectively. With up to 150 FTC, splitting tensile strength and failure modes of composite specimens were experimented. Results showed that air-entraining agent in the repairing mortar greatly influenced adhesive tensile strength under FTC. The water cement ratio and air-entraining agent of substrate concrete insignificantly affected the adhesive interface, but affects failure mode. The adhesive tensile strength of PCM-repaired composite specimens decreased faster than that of ordinary Portland cement mortar-repaired composite specimens although PCM itself showed stronger freeze-thaw resistance than ordinary mortar.

In the field of automatic optical inspection (AOI), defect recognition for an integrated circuit (IC) solder joint is a long-standing task. Inspired by a visual background extraction (ViBe) algorithm, an object detection method in computer vision, we propose a new inspection method for IC solder joints with an improved ViBe algorithm. To the best of our knowledge, we are the first to consider the defect inspection problem as an object detection problem. We build a solder joint model using the ViBe model updating scheme. Then, we compare the solder joint image with the well-trained model to detect potential defects. Finally, we introduce a frequency map method and define a metric named defect degree to evaluate the qualities of the solder joints. Experimental results show that our method is universal, accurate, and easily debugged compared with the other existing methods.

The material flow mechanism affects the printing quality considerably in 3D cementitious material printing (3DCMP) area. A numerical model was developed to investigate the material flow mechanism during the extrusion and deposition process. To quantify the effects of flow mechanism on the filament printing quality, deformation of the printed filament was proposed. Then a Support Vector Machine (SVM) was employed to study various factors on flow mechanism, hence the deformation of the printed filament. The SVM model results showed that deformation of the printed filament is independent of plastic viscosity, however, material yield stress and relative nozzle travel speed significantly affect the deformation of the printed filament. Lastly, an empirical parametric associative model was proposed to predict the filament deformation based on material yield stress and relative nozzle travel speed. National Research Foundation (NRF) Accepted version This research is supported by the National Research Foundation, Prime Minister's Office, Singapore under its Medium-Sized Centre funding scheme, Sembcorp Design & Construction Pte Ltd, and Sembcorp Architects & Engineers Pte Ltd.

The Qingchengzi Au–Ag orefield is a key Au province in the North China Craton. The fault-controlled orebodies are hosted in the Paleoproterozoic meta-sedimentary rocks of the Dashiqiao and Gaixian Formations. We present new bulk-ore REE, fluid inclusion (FI) microthermometric and mineral H–O–S–Pb isotopic data of these Au–Ag deposits, and discuss their ore fluid/material source and metallogenesis. Our FI microthermometric data indicate that the ore fluids are of medium temperatures (260–310 °C), low salinity (≤10 wt% NaCl eq.), and belonged to a H2O–CO2–NaCl system. Hydrogen (δD = –6.5 to 9.1‰) and oxygen (δ18O = –139.4 to –90.1‰) isotopes of the hydrothermal quartz indicate that the early-stage ore-forming fluids were mainly magmatic sourced. The δ34S values (–12.5 to 18.7‰) of the ore sulfides overlap with the Paleoproterozoic ore host (δ34S = –0.5 to 13.2‰) and the Late Triassic granites (δ34S = 5.6–7.6‰). Lead isotope compositions of the ore sulfides (206Pb/204Pb = 17.269–18.334; 207Pb/204Pb = 15.335–15.883; 208Pb/204Pb = 37.254–38.784) also support a metallogenic link with the granites and wall-rocks. Therefore, we suggest that the Qingchengzi Au–Ag deposits are best classified as magmatic-related medium-temperature hydrothermal lode type, albeit spatial correlations with magmatic intrusions are not ubiquitous. Closer to the hydrothermal centers, the higher-temperature, magmatic-dominated fluids were responsible to generate the Au(-Ag) mineralization, whereas the more distal, lower-temperature magmatic-meteoric-mixed fluids may have formed the Ag and Pb–Zn mineralization. The ore-forming fluids and materials were likely sourced mainly from the Triassic granitoids, although significant contributions of ore metals and sulfur from the Au-/Ag-rich Dashiqiao and Gaixian Formations should not be neglected. Considering the regional tectonic setting, the Late Triassic Qingchengzi Au–Ag polymetallic mineralization may have occurred during the post-collisional extension after the Yangtze-North China continent–continent collision.

At sufficiently low applied shear deformation or shear stress, fresh cement paste exhibits viscoelastic solid-like behavior. This solid-like state is particularly important for some applications, such as self-consolidating concrete formwork pressure and 3D concrete printing. In this study, the viscoelastic solid-like behavior of fresh cement pastes is probed using a rheometer. Static yield stress, storage modulus, and cohesion are measured by creep recovery and constant shear rate test, small amplitude oscillatory sweep (SAOS) test and tack test, respectively. The effect of nanoclay addition is studied in various aspects of viscoelastic performance of fresh cement pastes. It is found that nanoclay addition not only enhances yield stress and cohesion, but also stiffness in terms of storage and tangent modulus.

This study compares the differences and similarities of two types of superplasticizers—NSF (Naphthalene Sulfonate Formaldehyde) and PCE (PolyCarboxylate Ester)—in fresh cement paste systems, in terms of adsorption, dynamic yield stress, and thixotropic index. Results show that with either NSF or PCE addition, the more superplasticizer is added, the more it is adsorbed and the more it remains in the interstitial pore solution. The dynamic yield stress and thixotropic index also decrease with increasing addition the amount of either superplasticizer. However, NSF is less efficient in decreasing the dynamic yield stress than PCE. More importantly, the decreasing patterns of dynamic yield stress and thixotropic index are different with NSF and PCE additions; this is tied to the adsorption and dispersing mechanisms of these two types of superplasticizers.

An advancing technology that combines the concrete extrusion with a motion control to create structures with complex geometrical shapes without the need for formwork is known as 3D concrete printing. Since this technique prints layer by layer, the time taken to reach the same position in the subsequent layer is important as it will create an anisotropic property that has a weaker tensile strength at the bond interface of the two printed filaments. Through rheological measurement, which reveals the material deformation and flow behaviour, it is possible to examine the material structural build-up due to time-gap effect by measuring at different time delay. This paper focuses on investigating the time-gap effect on the printed filament with rheological and observation at macroscopic-scale to understand the material behaviour of the initial and subsequent printed layer during its fresh phase. Rheological experiment findings reveal that the tensile strength of the printed specimen is correlated to the material modulus at the initial layer. NRF (Natl Research Foundation, S’pore) Accepted version

Polycarboxylate ether surperplasticizer (PCE) has been commonly used and studied to enhance flowability of cementitious materials. However, the effect of PCE addition on thixotropy and flocculation state has not gained enough attention. In this study, Focused Beam Reflectance Measurement (FBRM)-rheometer is coupled. The coupled setup could simultaneously measure both flocculation states in terms of chord length distribution of cement particles/agglomerates and rheological properties including dynamic yield stress and thixotropy. The effect of various PCE additions is explored, firstly by measuring the adsorption of PCE surfactants and the concentration of PCE surfactants in cement pore solution. It is found that the effect of PCE addition on dynamic yield stress, thixotropy and chord length distribution of paste particles/agglomerates are all bi-fold. The turning point is the Critical Micelle Concentration in cement pore solution. Results of more agglomerated flocculation states at low PCE addition are measured for the first time and further discussed.

There have been many cases of quickly deteriorated interfaces for external bonding with FRP and/or cementitious materials in actual structures. It seems that we have not known proper design method nor detailing for long-term durability after being strengthened by external bonding. There are many factors for durability of the interface. This paper presents the results of recent studies on interface bonding property under effects of moisture and temperature, which are both single effect and combined effects, in the cases of both external bonded FRP and cementitious materials. The testing conditions include (1) wet condition for 18 months, (2) wet and dry cycles for one and half month, (3) combined wet/dry and temperature (both cases above and below freezing points) cycles, etc. There have been clear effects of both moisture and temperature on the interface bonding properties due to sensitivity of resin property. Generally, the effects of temperature are greater than those of moisture. The great combined effects of moisture and temperature were found under freeze thaw cycles under full immersion. The effects of moisture and temperature are less significant in case of rougher surface of substrate concrete. At the end of paper the design method for long-term durability of concrete structure strengthened by external bonding with FRP or cementitious materials is briefly discussed. And the current code drafting activities on external bonding in fib and Japan are introduced.

The dynamic and static yield stress of fresh cement mortar were measured in a rotational rheometer with a vane geometry using shear rate and shear stress-controlled protocols, respectively. Through a shear rate-controlled steady-state protocol, the equilibrium flow curve is measured and fitted with the Bingham model to obtain dynamic yield stress. A negative slope in the equilibrium flow curve, shear banding and stick-slip phenomena are observed and discussed. Through a stress-controlled creep-recovery protocol, viscosity bifurcation behavior is captured and static yield stress is marked as the creep stress when the bifurcation occurs. Finally, the discrepancy between dynamic and static yield stress is tied to thixotropy.

Shear-induced particle migration is widely recognized to be a challenge in characterizing the rheological properties of fresh cement-based mortars. In this study, we aim to quantify shear-induced particle migration by characterizing the stress decay process during constant shear flow with the aid of a modified thixotropy/migration model. It is found that a conventionally used single exponential model is not sufficient to fit the stress decay and describe the destructuration and sand migration of mortar under shear. Instead, a two exponential model is needed to capture the interaction of sand particles and the suspending cement paste phase. Model parameters are used to quantify the effect of sand volume fraction, clay addition, and applied shear rate on the kinetics and intensity of colloidal deflocculation and sand migration. Results provide evidence that the colloidal and granular contributions to the overall stress decay of mortars can be represented by each of the two exponentials.

In this paper, we construct a new type of mobile wireless data sinking platform for data collection based on unmanned aerial vehicle (UAV) technology, which aims to address the increasing demand for wireless sensor network (WSN) distribution in different monitoring areas and enlarge the coverage for various application scenarios. A wireless environmental monitoring system is firstly studied, and then wireless communication capacity and data collection experiments are performed. The communication capacity test results show that when the RF modules operate with a transmission power above 1 dBm and a communication distance below 100 m, the UAV wireless sink node can maintain a high quality communication data link. Additionally, an outdoor data collection experiment is performed using this UAV platform within a mountainous area. In this outdoor experiment, the data analysis results show that the validity rate of the environmental data that is obtained from the WSN cluster head node on the ground is higher than 92%, and most of the missing data results from WSN communication failures. This experiment proves the feasibility of introducing UAV as a sink node in a clustering WSN. The overall contributions of this paper can provide guidance for building a UAV cooperative WSN system in future.

Nanoclay, a thermal treated, purified attapulgite clay, has been used to increase thixotropy. However, the effect of nanoclay in presence of water reducing agent, such as PCE, on rheology, and the compatibility between nanoclay and PCE have not been well studied. The dynamic yield stress, thixotropic index, characteristic time, and microstructure of fresh cement pastes with combination of nanoclay and PCE addition are measured. It is found that nanoclay has a good compatibility with PCE. Nanoclay increases the dynamic yield stress and enhances the thixotropy of fresh cement pastes with and without PCE addition. The nanoclay addition agglomerates the microstructure at high PCE addition and increases the thixotropic index from bottom value to a high value. This study gives insight of achieving low dynamic yield stress yet high static yield stress and thixotropy mixtures.