Despite the key advantages of Fiber Reinforced Polymer (FRP) composites, they are susceptible to Barely Visible Impact Damage (BVID) under transverse loadings. This study investigates BVID in two ...quasi-isotropic carbon/epoxy laminates under quasi-static indentation and Low-Velocity Impact (LVI) loadings using Acoustic Emission (AE). First, the evolution of interlaminar and intralaminar damages is studied by analyzing the AE signals of the indentation test using b-value and sentry function methods. Then, the specimens are subjected to the LVI loading and the induced damages are compared with the indentation test and the percentage of each damage mechanism is calculated using Wavelet Packet Transform (WPT). In consistent with the mechanical data, ultrasonic C-scan and digital camera images of the specimens, the AE results show a considerable similarity between the induced BVID under quasi-static indentation and LVI tests. Finally, the obtained results show that AE is a powerful tool to study BVID in laminated composites under quasi-static and dynamic transverse loadings.
Monitoring metabolites at the point of care could improve the diagnosis and management of numerous diseases. Yet for most metabolites, such assays are not available. We introduce semisynthetic, ...light-emitting sensor proteins for use in paper-based metabolic assays. The metabolite is oxidized by nicotinamide adenine dinucleotide phosphate, and the sensor changes color in the presence of the reduced cofactor, enabling metabolite quantification with the use of a digital camera. The approach makes any metabolite that can be oxidized by the cofactor a candidate for quantitative point-of-care assays, as shown for phenylalanine, glucose, and glutamate. Phenylalanine blood levels of phenylketonuria patients were analyzed at the point of care within minutes with only 0.5 microliters of blood. Results were within 15% of those obtained with standard testing methods.
Sistem parkir otomatis merupakan salah satu teknologi manajemen parkir yang saat ini banyak digunakan di berbagai instansi. Sistem parkir otomatis merupakan sistem parkir yang bekerja dengan ...menempatkan sebuah mesin portal parkir. Mesin portal parkir tersebut kemudian secara otomatis dapat membuka dan menutup portal serta merekam nomor kendaraan saat masuk dan keluar dengan menggunakan sebuah kunci akses berupa smart card. Salah satu kendala dalam penerapan sistem parkir otomatis adalah terjadinya kemacetan apabila kondisi lalu lintas sedang tinggi. Hal tersebut terjadi karena unit kontrol pada sistem parkir otomatis memerlukan waktu yang relatif lama saat melakukan proses pengambilan dan penyimpanan citra dari kamera. Dalam penelitian ini, dilakukan pengujian pada beberapa platform sistem tertanam yang nantinya digunakan sebagai unit kontrol pada sistem parkir otomatis, yaitu Raspberry Pi 3B, Raspberry Pi 4B, dan Orange Pi Zero Plus. Tujuan pengujian tersebut adalah untuk mencari platform unit kontrol terbaik dengan beberapa kriteria, yaitu memiliki waktu respons tercepat saat mengambil citra, memiliki waktu respons tercepat saat menyimpan citra, dan memiliki konsumsi daya yang rendah. Dari pengujian yang dilakukan, didapatkan hasil bahwa platform Raspberry Pi 4B memiliki waktu respons tercepat untuk mengambil dan menyimpan citra dengan waktu rata-rata sebesar 1.827,9 ms, sedangkan konsumsi daya terendah dicapai oleh platform Orange Pi Zero Plus dengan nilai sebesar 1,9 W. Dari hasil pengujian yang telah dilakukan, Raspberry Pi 4B direkomendasikan sebagai unit kontrol pada sistem parkir otomatis apabila sistem parkir otomatis memerlukan perangkat dengan kinerja tinggi. Sementara itu, jika sistem parkir otomatis memerlukan perangkat yang hemat daya, Orange Pi Zero Plus direkomendasikan sebagai unit kontrol pada sistem parkir otomatis.
Salah satu faktor pada pengoperasian sel surya agar didapatkan nilai maksimum adalah posisi sel surya terhadap matahari. Solar tracker adalah alat untuk meningkatkan insolasi pada panel surya dengan ...mengubah arah panel surya menuju posisi matahari. Pada awalnya, solar tracker diatur menggunakan LDR. Kemudian, pengaturan berbasis pengolahan citra dapat mengurangi kesalahan pelacakan. Solar tracker berbasis citra selama ini masih menggunakan komputer ukuran penuh yang membutuhkan banyak energi dan tempat. Makalah ini bertujuan meningkatkan akurasi arah panel surya dan mengoptimalkan keluaran panel surya dengan meningkatkan sudut penyinaran matahari (insolasi) menggunakan solar tracker dengan sensor kamera dan komputer mini Raspberry Pi. Penggunaan kamera ditujukan untuk mengurangi kesalahan sistem berbasis LDR dan penggunaan Raspberry Pi menggantikan kerja komputer ukuran penuh. Pencarian orientasi matahari menggunakan metode intensitas nilai piksel tertinggi. Berdasarkan hasil analisis, keluaran panel surya terbukti dapat dioptimalkan dengan diaplikasikannya Solar Tracker Berbasis Kamera Terintegrasi Raspberry Pi. Perbandingan daya keluaran antara panel surya diam dengan panel surya yang terpasang pada Solar Tracker Berbasis Kamera Terintegrasi Raspberry Pi adalah 1:1,389 (21,5487 W:29,8822 W) pada pengujian tanpa beban dan 1:1,2042 (6,0344 W:7,2671 W) pada pengujian dengan beban lampu pijar 12 V/5 W.
A distributed denial of service (DDoS) attack is an attempt to partially or completely shut down the targeted server with a flood of internet traffic. The primary aim of this attack is to disrupt ...regular traffic flow to the victim’s server or network. DDoS attacks are volumetric attacks, and non-legacy IoT devices with low security such as webcams, baby monitoring devices and printers are compromised to form a botnet. High traffic from compromised IoT devices is rerouted to servers to disrupt their regular services. DDoS attacks are to an extent covered in the research literature. However, existing research do not discuss all DDoS attacks on general servers and botnet attacks on IoT devices and suggest few detection and mitigation solutions which are limited to addressing attacks on the cloud environment. Existing survey focuses either on the cloud layer or the IoT layer. A complete survey of DDoS attacks for both IoT and the cloud environment is not present in the current literature. Our survey is a comprehensive approach which includes general DDoS attack motivations and specific reasons why attackers prefer IoT devices to launch DDoS attacks. Various attack methods to compromise IoT devices and tools used to deploy botnet-infected IoT devices for DDoS attacks on the cloud layer are presented. A detailed attack classification on IoT devices and the cloud environment is presented considering that IoT devices are first compromised and then used by attackers against their primary targets on the cloud layer. Various state-of-the-art defense measures in the current literature for defense against DDoS attacks are present. Suggestions to implement an essential first line of defense for IoT devices are suggested. Our paper, to the best of our knowledge, is first to provide a holistic study of DDoS attacks from IoT devices to the cloud environment.
•A microfluidic paper-based chip platform is proposed for benzoic acid detection.•The study is based on Janovsky reaction and combined with microfluidics technology.•Benzoic acid concentrations of 21 ...commercial food samples are measured.•The measurement results deviate by no more than 6.6% versus HPLC method.
An integrated microfluidic platform comprising a microfluidic paper-based analytical device (µPAD) and a portable detection system is proposed for the concentration detection of benzoic acid via Janovsky reaction theory. In the proposed approach, the reaction zone of the µPAD is implanted with 5 N sodium hydroxide and dried at 30 °C for 20 min. The benzoic acid sample is derived to 3,5-Dinitrobenzoic acid using KNO3 and H2SO4 at 40 °C for 40 min and is then dripped on the reaction zone of the µPAD. Finally, the µPAD is transferred to the portable detection system and heated at a temperature of 45 °C for 20 min on a hot plate to prompt a Janovsky reaction. The resulting color change of the detection zone is observed using a CMOS camera. The reaction color image is delivered to a smartphone via a connector and the benzoic acid concentration is determined using self-written RGB analysis software. The experimental results obtained using control samples with known benzoic acid concentrations in the range of 500–4000 ppm show that the R(ed) + B(lue) intensity (Y) and benzoic acid concentration (X) are related as Y = −0.0264 X + 408.79. Moreover, the correlation coefficient is equal to R2 = 0.9953. The proposed detection platform is used to measure the benzoic acid concentrations of twenty-one commercial food samples. It is shown that the concentration measurements deviate by no more than 6.6% from those obtained using a standard HPLC macroscale method. Overall, the results presented in this study show that the proposed integrated microfluidic paper-based chip platform provides a compact and reliable tool for benzoic acid concentration measurement purposes.
We report the implementation of a parallel microscopy system (96 Eyes) that is capable of simultaneous imaging of all wells on a 96-well plate. The optical system consists of 96 microscopy units, ...where each unit is made out of a four element objective, made through a molded injection process, and a low cost CMOS camera chip. By illuminating the sample with angle varying light and applying Fourier Ptychography, we can improve the effective brightfield imaging numerical aperture of the objectives from 0.23 to 0.3, and extend the depth of field from ±5 μm to ±15 μm. The use of Fourier Ptychography additionally allows us to computationally correct the objectives' aberrations out of the rendered images, and provides us with the ability to render phase images. The 96 Eyes acquires raw data at a rate of 0.7 frame per second (all wells) and the data are processed with 4 cores of graphical processing units (GPUs; GK210, Nvidia Tesla K80, USA). The system is also capable of fluorescence imaging (excitation = 465 nm, emission = 510 nm) at the native resolution of the objectives. We demonstrate the capability of this system by imaging S1P
-eGFP-Human bone osteosarcoma epithelial (U2OS) cells.
Individual thermal discomfort perception gives important feedback signals for energy efficient control of building heating, ventilation and air conditioning systems. However, there is few effective ...method to measure thermal discomfort status of occupants in a real-time and contactless way. A novel method based on contactless measurements of human thermal discomfort status was presented. Images of occupant poses, which are related to thermoregulation mechanisms, were captured by a digital camera and the corresponding 2D coordinates were obtained. These poses were converted into skeletal configurations. An algorithm was developed to recognize different poses related to thermal discomfort, such as hugging oneself or wiping sweat off the brow. The algorithm could recognize twelve thermal discomfort related human poses. These poses were derived from a questionnaire survey of 369 human subjects. Some other human subjects participated in the validation experiments of the proposed method. All twelve thermal discomfort related poses can be recognized effectively.
Display omitted
•12 human poses of thermal comfort were defined based on 369 questionnaires.•A contactless measurement method for thermal comfort was proposed.•10 sub-algorithms were constructed for poses recognition of thermal comfort.
Teknologi komputer saat ini telah banyak digunakan dalam pengembangan animasi atau permainan komputer. Salah satu teknologi itu adalah machinima yaitu suatu sistem yang menggunakan teknologi mesin ...grafik 3D untuk menghasilkan produk sinematik secara real time. Dalam proses pembuatan produk sinematik itu penempatan posisi kamera sangat memegang peranan penting. Penempatan posisi kamera ini tentu harus sesuai dengan kaidah-kaidah sinematografi. Penelitian ini akan mengusulkan sebuah pendekatan agen cerdas dengan multi perilaku untuk menempatkan kamera virtual dalam lingkungan virtual secara otomatis sesuai dengan gaya seorang sutradara. Setiap kamera virtual itu akan memiliki perilaku yang berbeda berdasarkan kaidah sinematografi sehingga memiliki Point of View (POV) yang berbeda. Untuk memberikan perilaku pada kamera virtual akan digunakan pendekatan berbasis logika fuzzy dengan menggunakan metode mamdani. Jumlah variabel masukan yang digunakan sejumlah tiga dan variabel keluaran sejumlah tiga dengan membership function antara tiga sampai lima. Penelitian ini akan menggunakan simulasi permainan komputer dengan tiga kamera virtual dengan perilaku yang berbeda untuk merekam adegan yang sama dan hasilnya akan divalidasi berdasarkan hasil pengamatan dengan komunitas juru foto. Pada akhirnya dapat diambil kesimpulan bahwa pendekatan logika fuzzy dapat digunakan untuk memberikan sebuah perilaku atau gaya sutradara pada kamera virtual.AbstractComputer technology is has been used widely in the development of animation or computer games. One of the technologies is machinima, a system that uses reak time 3D graphics engine technology to produce cinematic products. In the process of develop a cinematic product, camera positioning is a very important component. The camera positioning must be comply with cinematography’s rule. This research will propose an intelligent multi agent behavior to positining a virtual camera in a virtual environment automatically according to the director’s style. Each virtual camera will have a different behavior based on cinematographic rules so that it has a different Point of View (POV). To assign a behavior on the virtual camera will be based on fuzzy logic using the mamdani method. The number of input variables are three and the output variables are three with the number membership functions between three to five. This research will program a computer game simulation with three multi behavior virtual cameras to capture some scene and the results will be validated based on observations with the photographer community. Finally it can be concluded that the fuzzy logic approach can be used to assign some behavior to a virtual camera.
Cavitation is quite important for the diesel spray atomization and the combustion of air–fuel mixture. In this study, a high-speed CMOS camera equipped with a long-distance microscope was utilized to ...capture the transient cavitating flow and spray characteristics in real-size optical nozzles with needle motion. The transient cavitation images, including geometry-induced cavitation and vortex-induced string cavitation, were captured clearly in cylindrical-orifice nozzles and tapered-orifice nozzles, respectively. Besides, the agglomerated phenomenon of geometry-induced cavitation was visually captured and analyzed for the first time. It was found that the string cavitation in nozzle excites the instability of spray cone angle and it is synchronized with increase of spray cone angle. In addition, it is the string cavitation but not geometry-induced cavitation has a much larger contribution to the increase of spray cone angle. It is interesting that the influence of agglomerated geometry-induced cavitation on spray cone angle was prominent. Furthermore, both the nozzle orifice L/D ratio and sac types have significant influences on string cavitation and spray characteristics. The smaller L/D ratio and VCO-type nozzles are prone to incur the stronger string cavitation, and then spray cone angle is obviously larger.
PDF
