Large-scale additive manufacturing processes for construction utilise computer-controlled placement of extruded cement-based mortar to create physical objects layer-by-layer. Demonstrated ...applications include component manufacture and placement of in-situ walls for buildings. These applications vary the constraints on design parameters and present different technical issues for the production process. In this paper, published and new work are utilised to explore the relationship between fresh and hardened paste, mortar, and concrete material properties and how they influence the geometry of the created object. Findings are classified by construction application to create a matrix of issues that identifies the spectrum of future research exploration in this emerging field.
This paper proposes a new method for stability analysis of a bidirectional dual full-bridge dc-dc converter with triple phase-shift control under arbitrary parameter changes. The present analysis ...makes the stability determination of these power converters more systematic and precise than the existing methods in this field, which are largely based on simulation. Nonlinear and periodic operation of the bidirectional converter is presented including the control circuit. Using the working theory, the converter operation is separated into several stages. Equivalent circuits and state equations are developed for each stage. The Lyapunov function method is used to determine the stability of the converter in every stage. Justification is provided for the absence of abrupt changes of the state variables or infinite noise at the interface of different stages. The stability of the bidirectional converter is determined theoretically by integrating these concepts. Some simulation results are provided to validate the developments.
Insect Growth Regulator (IGR) novaluron is an alternative to synthetic neuro-inhibitory insecticides. Present study was designed to assess appropriate dosages of novaluron for dengue vector control. ...Larvae of Aedes aegypti and Ae. albopictus were exposed to a concentration series of novaluron (Rimon EC10) for two fixed exposure periods of 7-days and 14-days to determined LC
and LC
values. Inhibition of adult emergence (IE
and IE
) was determined by a 14-day exposure. Semi-field experiments were conducted by exposing cohorts of Ae. aegypti larvae to IE
, 2 × IE
and 10 × IE
novaluron concentrations in water storage buckets (10 L) and plastic barrels (200 L). For the 7-day exposure, LC
values were 0.047-0.049 ppm and LC
were 0.144-0.151 ppm. For 14-day exposure, these values were 0.002-0.005 ppm and 0.006-0.01 ppm respectively. For both species, IE
was 0.001 ppb under semi-field conditions, and was effective for nearly 2 months. Novaluron concentration 0.01 ppb was effective up to 3 months, with an IE of 89-95%. Authorities should critically review a reduction of the presently recommended field dosage of 200 ppm novaluron by × 100 or more. This would provide the same efficacy but mitigate environmental pollution, development of vector resistance, and financial losses.
Condition monitoring and fault diagnosis are important for maintaining the system performance and guaranteeing the operational safety. The traditional data-driven approaches mostly incorporate ...well-defined features and methodologies such as supervised artificial intelligence algorithms. Prior knowledge of possible features and a large quantity of labelled condition data are needed. Besides, many traditional approaches require rebuilding or a retraining of the original model to diagnosis new conditions. The present study proposes an intelligent fault diagnosis approach that uses a deep neural network (DNN) based on stacked denoising autoencoder. Representative features are learned by applying the denoising autoencoder to the unlabelled data in an unsupervised manner. A DNN is then constructed and fine-tuned with just a few items of labelled data. The trained DNN achieves high performance in fault classification. Furthermore, new conditions can be correctly classified by simply fine-tuning the trained DNN model using a small amount of labelled data under the new conditions. The effectiveness of the proposed approach is evaluated using a case study of fault diagnosis of a bearing unit. The results indicate that the proposed method can extract representative features from massive unlabelled data on the system condition and achieve high performance in fault diagnosis.
•We propose a novel alignment method to construct a common feature space under the guidance of a Gaussian prior for UDA.•We introduce a new method to align two distributions by minimizing the direct ...L1-distance between the decoded samples.•The proposed work achieves state-of-the-art performance on both digit and object classification tasks.
In this paper, we focus on the unsupervised domain adaptation problem where an approximate inference model is to be learned from a labeled data domain and expected to generalize well to an unlabeled domain. The success of unsupervised domain adaptation largely relies on the cross-domain feature alignment. Previous work has attempted to directly align features by classifier-induced discrepancies. Nevertheless, a common feature space cannot always be learned via this direct feature alignment especially when large domain gaps exist. To solve this problem, we introduce a Gaussian-guided latent alignment approach to align the latent feature distributions of the two domains under the guidance of a prior. In such an indirect way, the distributions over the samples from the two domains will be constructed on a common feature space, i.e., the space of the prior, which promotes better feature alignment. To effectively align the target latent distribution with this prior distribution, we also propose a novel unpaired L1-distance by taking advantage of the formulation of the encoder-decoder. The extensive evaluations on nine benchmark datasets validate the superior knowledge transferability through outperforming state-of-the-art methods and the versatility of the proposed method by improving the existing work significantly.
We investigated the physicochemical properties and the biotic interactions of breeding sites of tropical mosquito species. Field sampling was done in 12 study areas in Sri Lanka covering areas with ...secondary natural forests and human settlements. A total of 226 breeding sites were investigated to determine the biotic interactions and physiochemical properties of breeding water (pH, Conductivity, Dissolved Oxygen, Total Dissolved Solids and Temperature). A total of 80.5% of breeding sites from both habitats were positive for mosquito larvae of seven genera and 24 species. Orthopodomyia flavithorax (297) and Aedes albopictus (295) were dominated in tree holes of Alstonia macrophylla, Vateria copallifera and Artocarpus nobilis. Diversity indices showed that the diversity of mosquitoes is high in wet zone habitats of Sri Lanka compared to dry and intermediate zone habitats. Aedes albopictus coexisted with 11 different mosquito species while it avoided larvae of Culex fuscanus, Cx. uniformis and Tripteroides affinis. Strong positive associations were reported between Ae. albopictus and Ar. subalbatus while larvae of Or. flavithorax mosquitoes were not co‐occurred with the larvae of Ae. vittatus, Ae. aegypti, Cx. sitiens, Ar. subalbatus, Anopheles spp and Tr. affinis. The findings identified the breeding adaptability and tolerance to a wide range of physiochemical properties of tropical mosquito communities.
Tropical mosquitoes tolerate a wider range of physiochemical properties (Temperature from 19.8 to 36.8°C, pH between 4.2 and 8.4).
Tree holes of Alstonia macrophylla, Vateria copallifera and Artocarpus nobilis are preferred by Orthopodomyia flavithorax and Aedes albopictus.
Aedes albopictus mostly coexists with larvae of Armigeres subalbatus and avoids the larvae of Culex fuscanus, Cx uniformis and Tripteroides affinis.
We report the larvicidal effects of four different morphologies of zinc oxide nanoparticles (ZnO NPs) star-shaped (S), needle-like (N), plate-like (P) and cubical (C) on larvae of
Aedes albopictus
...and
Anopheles vagus
; the mosquitoes causing dengue fever and malaria, respectively. The nanoparticles were characterized by several analytical techniques, and their sizes and shapes were determined. Second instar larvae of the two types of mosquitoes were exposed to several concentrations of nanoparticles (25 mg L
−1
, 50 mg L
−1
, 75 mg L
−1
, 100 mg L
−1
) at 25 ± 2 °C and 84 ± 5% R.H, separately, for each morphology. Larval mortality was reported at 24 h intervals up to 21 days. The resulting LC
50
for
Aedes albopictus
were, respectively, 38.90 mg L
−1
, 47.53 mg L
−1
, 68.38 mg L
−1
, 50.24 mg L
−1
for S-, N-, P- and C-shaped nanoparticles. The LC
50
of
Anopheles vagus
is lower (LC
50
4.78 mg L
−1
, 6.51 mg L
−1
, 13.64 mg L
−1
, 10.47 mg L
−1
), respectively, for S-, N-, P- and C-shaped nanoparticles indicating that the nanoparticles are more toxic to
Anopheles vagus
larvae. The highest larvicidal effect was obtained from star-shaped nanoparticles
Aedes albopictus
(38.90 mg L
−1
) on
Anopheles vagus
(4.78 mg L
−1
), and the lowest was shown by the plate-like nanoparticles
Aedes albopictus
(68.38 mg L
−1
),
Anopheles vagus
(13.64 mg L
−1
). The rate of development of surviving mosquito larvae was retarded when exposed to ZnO nanoparticles suggesting the possibility for these nanoparticles to kill and delay the growth of
Aedes albopictus
and
Anopheles vagus
larvae.
We report the larvicidal impacts of four different morphologies of zinc oxide nanoparticles (ZnO NPs) star-shaped (S), needle-like (N), plate-like (P), and cubical (C) on mosquito larvae of
Aedes albopictus
and
Anopheles vagus
.
This paper proposes a global iterative sliding mode control approach for high-precision contouring tasks of a flexure-linked biaxial gantry system. For such high-precision contouring tasks, it is the ...typical situation that the involved multi-axis cooperation is one of the most challenging problems. As also would be inevitably encountered, various factors render the multi-axis cooperation rather difficult; such as the strong coupling (which naturally brings nonlinearity) between different axes due to its mechanical structure, the backlash and deadzone caused by the friction, and the difficulties in system identification, etc. To overcome the above-mentioned issues, this work investigates an intelligent model-free contouring control method for such a multi-axis motion stage. Essentially in the methodology developed here, it is firstly ensured that all the coupling, friction, nonlinearity, and disturbance (regarded as uncertain dynamics in each axis) are suitably posed as uncertainties; and then a varying-gain sliding mode control method is proposed to adaptively compensate for the matched unknown dynamics in the time domain, while an iterative learning law is applied to suppress the undesirable effects arising from the remaining repetitive matched and unmatched uncertainties in the iteration domain. With this approach, the chattering that typically results from the over-estimated control gains in the sliding mode control is thus suppressed during the iterations. To analyze the contouring performance and show the improved outcomes, rigorous proof is furnished on both the stability in the time domain and the convergence in the iteration domain; and the real-time experiments also illustrate that the requirements of precision motion control towards high-speed and complex-curvature references can be satisfied using the proposed method, without prior knowledge of the boundary to the unknown dynamics.
This study evaluated potential genotoxic and histopathological effects of nano-TiO2 (0.1, 0.5 and 1 mg/L) in Nile tilapia over 7, 14 and 21 days of exposure. Bulk TiO2 (1 mg/L) along with controls ...was used for comparison. Comet assay revealed that nano-TiO2 can induce erythrocytic DNA damage in a concentration dependent manner. However, micronuclei induction was observed only at the lowest concentration. Elevated organ damage indices indicate nano-TiO2 induced histological alterations in liver and intestine. Severe histological alterations induced by nano-TiO2 in the fish were necrosis of hepatic parenchyma and intestinal mucosa. Bulk TiO2 exposure had no effect on the histological structure of the intestine but increased liver damage indices and erythrocytic DNA damage compared to the controls indicating dissolved form of TiO2 is not biologically inert. More research efforts are needed to generate in vivo toxicity data on realistic levels of nano-TiO2 and bulk TiO2 for environmental risk assessments.
•Nile tilapia was used as a tropical fish model to assess nanotoxicity.•Genotoxicity of nano-TiO2 was confirmed based on erythrocytic DNA damage.•Histological alterations in liver and intestine were induced by nano-TiO2.•Bulk TiO2 caused erythrocyte DNA damage and histological alterations in liver.•Bulk form of TiO2 is not biologically inert.
The destructive nature of debris flows is mainly caused by flow bulking from entrainment of an erodible channel bed. To arrest these flows, multiple flexible barriers are commonly installed along the ...predicted flow path. Despite the importance of an erodible bed, its effects are generally ignored when designing barriers. In this study, three unique experiments were carried out in a 28 m long flume to investigate the impact of a debris flow on both single and dual flexible barriers installed in a channel with a 6 m long erodible soil bed. Initial debris volumes of 2.5 and 6 m
3
were modelled. For the test setting adopted, a small upstream flexible barrier before the erodible bed separates the flow into several surges via overflow. The smaller surges reduce bed entrainment by 70% and impact force on the terminal barrier by 94% compared to the case without an upstream flexible barrier. However, debris overflowing the deformed flexible upstream barrier induces a centrifugal force that results in a dynamic pressure coefficient that is up to 2.2 times higher than those recommended in guidelines. This suggests that although compact upstream flexible barriers can be effective for controlling bed entrainment, they should be carefully designed to withstand higher impact forces.
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