Geometric Perspective on Kinematics and Singularities of Spatial Mechanisms

This doctoral dissertation deals with the kinematics and singularity analyses of serial and parallel manipulators with multiple working modes. The inverse kinematics of 6R architectures with non-spherical wrists were solved using simple geometric considerations; the problem was reduced to the solution of a trigonometric equation in one variable, the sixth joint angle. The direct kinematic analysis of the parallel manipulator, namely the Exechon, was conducted; it involves using a standard numerical tool to solve the system of equations in platform\u2019s angle variables. Both kinematics analyses took advantage of the standard numerical solver to obtain the solutions. The singularities of the Exechon were studied with the geometrical interpretation. By using the theory of reciprocal screws, the input-output velocity equations were introduced. This led to the investigation of the Jacobian matrices, which is an essential part when working with any manipulator. A method for obtaining the singularity loci and the numerical example was provided. The formulations presented in this dissertation are general and effective enough to be applicable for many other similar architectures

Liquid pumping and mixing by PZT synthetic jet

In this paper, a PZT synthetic jet that can function as both an efficient pumping and mixing device is developed. Compare with the conventional design where the practice of controlling the internal flow is undertaken by microvalves structure, this approach promotes the durability and allows the device to work with different liquids at high Reynold number without losing of backflow from the diffuser, therefore provides efficient mixing. The pumping performance is applicable for commercialized counterparts while the homogeneous medium was obtained at downstream in the experiments, which was further confirmed by simulation. Notably, the chaotic mixing feature of the device is also applicable for immiscible liquids with the micro-droplet formation result at the outlet

Development of a PCB-based passive capacitive sensor for fluidic flow detection

A passive wireless sensor system integrated with capacitive fluidic flow detection is proposed and developed based on the printed circuit board (PCB) technique. The capacitive sensing structure consists of PCB-based electrodes enclosing an insulating pipe that contains the fluidic flow of interest. The conductivity of the fluidic flow and the appearance of foreign objects within the flow can be determined by analysing the resonant frequency of the detection path in the proposed system. Experimental results demonstrate that the resonant frequency increases according to the increase in electrical conductivity of the fluidic flow. In addition, the sensing performance is also confirmed by the detection of sizes and electrical conductivities of NaCl droplets passing through the detection zone. Furthermore, this work indirectly verifies the effectiveness and feasibility of the integration of passive wireless sensing technique into the fluidic flow detector by using the PCB fabrication technique and demonstrates great potential for use in various applications in biomedical and chemical fields, especially in biomedical applications

CHẾ TẠO VÀ TÍNH CHẤT CỦA VẬT LIỆU TỔ HỢP GRAPHENE – ỐNG NANO CÁCBON – HẠT NANO VÀNG

In this work, a composite nanomaterial consisting of graphene (Gr), double-wall carbon nanotube (DWCNTs) and gold nanoparticles (AuNPs), designated as DWCNTs-AuNPs-Gr was synthesized via the thermal chemical vapour deposition technique. The morphology and electrical and electrochemical properties of the material were characteried by using field emission scanning electron microscopy, Raman spectroscopy, four-probe sheet resistance measurement, and cyclic voltammetry (CV). The average sheet resistance value of DWCNTs-AuNPs-Gr is 549 W/sq, 2.3 times lower than that of graphene. The current response of a DWCNTs-AuNPs-Gr-modified electrode in a 2 mM K3[Fe(CN)6]/K4[Fe(CN)6] solution with 0.1 M PBS is 15.79 µA, 1.48 times higher than that of a graphene-modified electrode and 2.57 times higher than that of a bare electrode. The DWCNTs-AuNPs-Gr material can be used for electrochemical biosensors to detect various bioelements.Trong công trình này, màng tổ hợp của vật liệu graphene (Gr) – ống nano cácbon hai tường (DWCNT) và hạt nano kim loại vàng (AuNPs) (DWCNT-AuNPs-Gr) đã được chế tạo bằng phương pháp lắng đọng pha hơi nhiệt hóa học (CVD). Hình thái học bề mặt và các tính chất điện, điện hóa của vật liệu tổ hợp đã được khảo sát thông qua kính hiển vi điện tử quét phát xạ trường, phổ Raman, điện trở bốn mũi dò và kỹ thuật quét thế vòng (CV). Với nồng độ DWCNTs 0,3 g/L và tốc độ quay phủ 4000 vòng/phút, vật liệu DWCNTs-AuNPs-Gr có điện trở bề mặt giảm 2,3 lần so với màng Gr và đạt khoảng 549 W/sq; dòng đỉnh đáp ứng trong dung dịch 2 mM K3[Fe(CN)6]/K4[Fe(CN)6] trong 0,1 M PBS đạt 15,79 µA tại 50 mV/s, cao gấp 1,48 lần so với điện cực biến tính màng Gr và gấp 2,57 lần so với điện cực trần. Vật liệu DWCNTs-AuNPs-Gr có tiềm năng ứng dụng trong cảm biến điện hóa để phát hiện các phần tử sinh học khác nhau

CSA: Thực hành nông nghiệp thông minh với khí hậu ở Việt Nam

During the last five years, Vietnam has been one of the countries most affected by climate change. Severe typhoons, flooding, cold spells, salinity intrusion, and drought have affected agriculture production across the country, from upland to lowland regions. Fortunately for Vietnam, continuous work in developing climate-smart agriculture has been occurring in research organizations and among innovative farmers and entrepreneurs. Application of various CSA practices and technologies to adapt to the impact of climate change in agriculture production have been expanding. However, there is a need to accelerate the scaling process of these practices and technologies in order to ensure growth of agriculture production and food security, increase income of farmers, make farming climate resilient, and contribute to global climate change mitigation. This book aims to provide basic information to researchers, managers, and technicians and extentionists at different levels on what CSA practices and technologies can be up scaled in different locations in Vietnam

Experience in Using Mobile Laboratory for Monitoring and Diagnostics in the Socialist Republic of Vietnam

The aim was to present the experience of using mobile laboratory for monitoring and diagnostics (MLMD) during the epizootiological monitoring of the northern provinces of Vietnam. MLMD was transferred by Federal Service for Surveillance in the Sphere of Consumers Rights Protection and Human Welfare to the Socialist Republic of Vietnam as part of implementation of cooperation programs on combating infectious diseases. The use of MLMD made it possible to obtain new information on the circulation of pathogens of natural-focal infectious diseases on the territory of Vietnam. It also provided the necessary conditions for conducting research using methods of express diagnostics, bacteriological analysis, performing a full cycle of work – from the receipt of samples to the disinfection and destruction of infected material in compliance with the requirements of biological safety in the field. The effectiveness of using mobile laboratories in response to the emergencies of sanitary and epidemiological nature, both to strengthen stationary laboratory bases and to organize diagnostic studies in remote regions, has been shown. The use of MLMD for the diagnosis of COVID‑19 has been an effective component of countering the new coronavirus infection in Vietnam and significantly increased the volume of testing in the country

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

PANET: a GPU-based tool for fast parallel analysis of robustness dynamics and feed-forward/feedback loop structures in large-scale biological networks.

It has been a challenge in systems biology to unravel relationships between structural properties and dynamic behaviors of biological networks. A Cytoscape plugin named NetDS was recently proposed to analyze the robustness-related dynamics and feed-forward/feedback loop structures of biological networks. Despite such a useful function, limitations on the network size that can be analyzed exist due to high computational costs. In addition, the plugin cannot verify an intrinsic property which can be induced by an observed result because it has no function to simulate the observation on a large number of random networks. To overcome these limitations, we have developed a novel software tool, PANET. First, the time-consuming parts of NetDS were redesigned to be processed in parallel using the OpenCL library. This approach utilizes the full computing power of multi-core central processing units and graphics processing units. Eventually, this made it possible to investigate a large-scale network such as a human signaling network with 1,609 nodes and 5,063 links. We also developed a new function to perform a batch-mode simulation where it generates a lot of random networks and conducts robustness calculations and feed-forward/feedback loop examinations of them. This helps us to determine if the findings in real biological networks are valid in arbitrary random networks or not. We tested our plugin in two case studies based on two large-scale signaling networks and found interesting results regarding relationships between coherently coupled feed-forward/feedback loops and robustness. In addition, we verified whether or not those findings are consistently conserved in random networks through batch-mode simulations. Taken together, our plugin is expected to effectively investigate various relationships between dynamics and structural properties in large-scale networks. Our software tool, user manual and example datasets are freely available at http://panet-csc.sourceforge.net/

ĐIỀU CHẾ THANH NANO GADOLINI HYDROXIT VÀ KHẢO SÁT HOẠT TÍNH XÚC TÁC CỦA HỆ UV/H2O2/Gd(OH)3

In this study, nano Gd(OH)3 was synthesized with the polyol method with gadolinium chloride hydrate (GdCl3·xH2O) and sodium hydroxide as precursors, and triethylene glycol (C6H14O4) as a surfactant. The material was characterized with XRD, SEM, TEM, TG-DTA, EDX techniques. Gd(OH)3 has the form of pure nanorods with a uniform size of 20 × 200 nm. The material was utilized as a catalyst in the advanced photochemical decomposition of red Congo as the UV/Gd(OH)3 and UV/H2O2/Gd(OH)3 system.Trong nghiên cứu này, vật liệu nano Gd(OH)3 dạng thanh đã được tổng hợp bằng phương pháp polyol với tiền chất là gadolini clorua hydrat (GdCl3·xH2O), natri hydroxit và chất hoạt động bề mặt là trietylen glycol (C6H14O4). Sản phẩm đã được đặc trưng bằng các kỹ thuật XRD, SEM, TEM, TG-DTA, EDX. Kết quả cho thấy vật liệu Gd(OH)­3 thu được có cấu trúc dạng thanh nano, đồng đều với khích thước 20 × 200 nm và tinh khiết. Vật liệu được ứng dụng trong phản ứng oxy hóa nâng cao đối với quang hóa phân hủy Congo đỏ của hệ xúc tác UV/Gd(OH)3 và UV/H2O2/Gd(OH)3

A geometrical approach to the inverse kinematics of 6R serial robots with offset wrists

The computation of the joint-Angle values of a 6R serial manipulator for a given end-effector pose is more difficult for architectures lacking the conventional spherical wrist. Despite this added complexity, such arms have increasingly gained acceptance as they provide better dexterity for a number of tasks. The paper presents a geometric-Analysis method for the inverse kinematics of a robot with an offset wrist. The sought postures are shown to correspond to the roots of four separate univariate trigonometric equations for the sixth joint angle. A standard numerical solver is applied to derive all sets of possible real solutions. By back-substitution, all the remaining angular variables are found in succession. Two particular arm designs are considered and full sets of solutions are obtained by the discussed approach. The method is easy to implement and can be applied to various 6R serial robots