Hierarchical Life-Cycle Design of Concrete Structures

Concrete structures’ service life lasts decades. In order to deal with all the probable degradations and deteriorations in the whole life span, the concept of concrete structures’ Life-Cycle Design was introduced into China in the 1980s. However, until this day, Life-Cycle Design is still more of a concept to most structure designers and engineers, rather than a practical method. This paper provides a hierarchical method for concrete structures’ Life-Cycle Design, in which the design process is divided into five levels. Safety should be the fundamental requirements for all concrete structures, so as to guarantee a reliable quality. For structures located in severe environments, durability design is necessary so as to ensure the designed service life. Further, when specific economic requirements are set for concrete structures, life-cycle cost (LCC) should be considered carefully in selecting the optimal scheme. Besides, those concrete structures designed to be environmental-friendly should also take into account the specific environmental assessment criteria. Nowadays, user-friendly schemes have attracted increasing attention too; therefore, customers’ demands should also be fully involved in the design process. Considering all the design levels mentioned above, diverse designing criteria are provided accordingly. This paper also uses a road bridge member which exposed to chloride attack in marine environment as an example to illustrate this hierarchical design method. Using the life-cycle-based hierarchical design method, a probable scheme that is safe, durable, economic, environmental friendly, and user friendly is provided

Behavior of Steel–Concrete Composite Beams with Corroded Shear Studs Under Negative Bending Moment

The behavior of corroded steel–concrete composite beams under hogging moment was studied by experimental investigation and theoretical analysis. A total of eight specimens, six of which had corroded shear studs, were tested. The corrosion rate of studs ranged from 0 to approximately 50%. The constant-current accelerated corrosion method was adopted to accelerate the corrosion process. The loading test results indicated that the bending capacity of the corroded beams decreased slightly with increasing corrosion ratio of the studs. The corroded beams also exhibited an obvious decrease in bending rigid stiffness and increase in the slip between the steel beam and the concrete slab. An analytical model was developed to study the steel–concrete composite beams with corroded studs under hogging moment. It is shown that the analytical model is able to predict the test results with reasonable accuracy

Behaviour of Corroded Stud Shear Connectors under Fatigue Loading

Experimental investigation was conducted on corroded composite push-out specimens to study the behavior of shear studs subjected to fatigue loading. A total of eight standard EC4 push-out specimens were tested. The expected corrosion rate of test specimens ranged from 0 to 50%. The main purpose of these tests was to determine the fatigue life and the reduction effect caused by the corrosion on the fatigue life. The effect of corrosion on the fatigue crack, load-slip curves, and failure modes was also studied. In addition, the test results were compared with current Eurocode design predictions, which is only for specimen without corrosion. It is shown that the current Eurocode design predictions are quite conservative for the test specimens in this study. Design equations were also proposed for fatigue life of corroded composite push-out specimens

A DNA-based pattern classifier with in vitro learning and associative recall for genomic characterization and biosensing without explicit sequence knowledge

BACKGROUND: Genetic material extracted from in situ microbial communities has high promise as an indicator of biological system status. However, the challenge is to access genomic information from all organisms at the population or community scale to monitor the biosystem’s state. Hence, there is a need for a better diagnostic tool that provides a holistic view of a biosystem’s genomic status. Here, we introduce an in vitro methodology for genomic pattern classification of biological samples that taps large amounts of genetic information from all genes present and uses that information to detect changes in genomic patterns and classify them. RESULTS: We developed a biosensing protocol, termed Biological Memory, that has in vitro computational capabilities to “learn” and “store” genomic sequence information directly from genomic samples without knowledge of their explicit sequences, and that discovers differences in vitro between previously unknown inputs and learned memory molecules. The Memory protocol was designed and optimized based upon (1) common in vitro recombinant DNA operations using 20-base random probes, including polymerization, nuclease digestion, and magnetic bead separation, to capture a snapshot of the genomic state of a biological sample as a DNA memory and (2) the thermal stability of DNA duplexes between new input and the memory to detect similarities and differences. For efficient read out, a microarray was used as an output method. When the microarray-based Memory protocol was implemented to test its capability and sensitivity using genomic DNA from two model bacterial strains, i.e., Escherichia coli K12 and Bacillus subtilis, results indicate that the Memory protocol can “learn” input DNA, “recall” similar DNA, differentiate between dissimilar DNA, and detect relatively small concentration differences in samples. CONCLUSIONS: This study demonstrated not only the in vitro information processing capabilities of DNA, but also its promise as a genomic pattern classifier that could access information from all organisms in a biological system without explicit genomic information. The Memory protocol has high potential for many applications, including in situ biomonitoring of ecosystems, screening for diseases, biosensing of pathological features in water and food supplies, and non-biological information processing of memory devices, among many. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1754-1611-8-25) contains supplementary material, which is available to authorized users

Effect of Corrosion on the Shear Transfer Behavior of Stud Shear Connectors

The effect of corrosion on the shear transfer behavior of stud shear connectors was investigated in this study. Experimental investigation was performed using an innovative test setup for single stud shear connector. Two series of specimens having different stud diameters were fabricated and tested. The test specimens were firstly corroded to different corrosion rates by electronic accelerating method. Loading test were then performed to obtain the load-slip curves and ultimate strengths of corroded test specimens. Corrosion rates were measured from the studs obtained from the failure test specimens. Test results were compared with standard push out test specimens having the similar corrosion rates. It is shown that the test results obtained from the single stud shear connectors are conservative compared with the corroded push test specimens, which prove the validation of single stud shear connector test method. The effect of corrosion on the shear transfer behavior of stud shear connectors was also presented

catena-Poly[[[bis­(3-hy­droxy­adamantane-1-carboxyl­ato-κO 1)(3-hy­droxy­adamantane-1-carb­oxy­lic acid-κO 1)zinc(II)]-μ2-4,4′-bipyridine] monohydrate]

In the title coordination polymer, {[Zn(C11H15O3)2(C10H8N2)(C11H16O3)]·H2O}n, the ZnII ion is five coordinated by two N atoms from two 4,4′-bipyridine (4,4′-bpy) mol­ecules and three O atoms from two 3-hy­droxy­adamantane-1-carboxyl­ate anions (L) and one 3-hy­droxy­adamantane-1-carb­oxy­lic acid (HL) mol­ecule. The resulting coordination polyhedron is a near regular ZnN2O3 trigonal bipyramid, with the N atoms in axial sites. The 4,4′-bpy mol­ecules [dihedral angle between the aromatic rings = 17.2 (2)°] act as bridges, connecting the metal ions into an infinite polymeric chain propagating in [01]. O—H⋯O hydrogen bonds help to consolidate the packing

Pie-like electrode design for high-energy density lithium–sulfur batteries

Owing to the overwhelming advantage in energy density, lithium–sulfur (Li–S) battery is a promising next-generation electrochemical energy storage system. Despite many efforts in pursuing long cycle life, relatively little emphasis has been placed on increasing the areal energy density. Herein, we have designed and developed a ‘pie’ structured electrode, which provides an excellent balance between gravimetric and areal energy densities. Combining lotus root-like multichannel carbon nanofibers ‘filling’ and amino-functionalized graphene ‘crust’, the free-standing paper electrode (S mass loading: 3.6 mg cm[superscript −2]) delivers high specific capacity of 1,314 mAh g[superscript −1] (4.7 mAh cm[superscript −2]) at 0.1 C (0.6 mA cm[superscript −2]) accompanied with good cycling stability. Moreover, the areal capacity can be further boosted to more than 8 mAh cm[superscript −2] by stacking three layers of paper electrodes with S mass loading of 10.8 mg cm[superscript −2].National Science Foundation (U.S.) (DMR-1120901)Wuxi Weifu High-technology Group Co., Ltd

Adversarial Reweighting for Speaker Verification Fairness

We address performance fairness for speaker verification using the adversarial reweighting (ARW) method. ARW is reformulated for speaker verification with metric learning, and shown to improve results across different subgroups of gender and nationality, without requiring annotation of subgroups in the training data. An adversarial network learns a weight for each training sample in the batch so that the main learner is forced to focus on poorly performing instances. Using a min-max optimization algorithm, this method improves overall speaker verification fairness. We present three different ARWformulations: accumulated pairwise similarity, pseudo-labeling, and pairwise weighting, and measure their performance in terms of equal error rate (EER) on the VoxCeleb corpus. Results show that the pairwise weighting method can achieve 1.08% overall EER, 1.25% for male and 0.67% for female speakers, with relative EER reductions of 7.7%, 10.1% and 3.0%, respectively. For nationality subgroups, the proposed algorithm showed 1.04% EER for US speakers, 0.76% for UK speakers, and 1.22% for all others. The absolute EER gap between gender groups was reduced from 0.70% to 0.58%, while the standard deviation over nationality groups decreased from 0.21 to 0.19