243 research outputs found
On the spatial and temporal coherence of wireless vehicular short range channels
No full textWe consider spatial and temporal coherence of the vehicle–to–vehicle (V2V) wireless communication channel with focus on a suburban residential highway. The dominant reflectors in such an environment are vehicles passing in the adjacent lane and houses
along the road. Instead of treating the reflectors as point targets, the V2V short range propagation environment requires partitioning of the illuminated reflector side into
sufficiently small tiles. The channel transfer function is obtained as a superposition of specular reflections from the tiles, the line–of–sight (LOS) component, and the ground reflection. The tile size is selected to ensure that the ratio of the tile area to the tile–to–receiver distance satisfies the far field conditions. The reflected power is described by the tile radar cross section (RCS). The bistatic physical optics RCS model is adapted to account for the tile’s orientation with respect to the ray geometry. We apply the superposition model to the numerical analysis of two general scenarios
for a 22MHz channel in the 2.4GHz band. The first scenario considers a single vehicle reflector passing in the lane adjacent to the V2V communication pair. Both the vector network analyzer (VNA) experiments and the tiling model analysis illustrate that repositioning of the reflector, the transmitter, or the receiver by a few centimeters results in change of the signal power by several decibels. The second scenario analysis characterizes the channel coherence statistics for the
suburban residential highway. We consider the V2V single lane LOS and non–LOS geometries, where in the latter the receiver is shadowed by a large vehicle. The reflectors are both houses and vehicles passing in the opposite direction. The measure of channel coherence is the normalized spatial covariance calculated by correlating transfer functions corresponding to feasible receiver position pairs and performing spatial smoothing. The area of feasible receiver positions is divided into contiguous squares
whose size ensures wide sense quasi–stationarity within the square. Irrespective of direction the correlation remains high and a typical sedan roof usually does not provide sufficient spacing to obtain average inter–antenna correlation lower than 0.5. The upper bound on coherence time extends over the transmission time of multiple packets for systems in the considered band, and does not allow for usable time diversity.Ph.D.Includes bibliographical referencesIncludes vitaby Haris Krem
Perkembangan Folikel Hasil Autotransplantasi Ovarium di Subkapsula Ginjal Setelah Induksi PMSG Pada Mencit (Mus musculus albinus)
No full textPenelitian ini dilakukan untuk mengetahui pengaruh induksi hormon pregnant'mare's serum gonadotrophin (PMSG) terhadap morfologi ovarium dan jumlah folikel pad a mencit yang mengalami autotransplantasi. Sebanyak 1 O ekor mencit betina strain ODY berumur 4 minggu dikoleksi ovariumnya dengan teknik ovariektomi. Ovarium dipotong menjadi dua bagian sama besar. Satu potongan ovarium difiksasi dalam larutan Bouin u.ntuk pemeriksaan histologi dan potongan yang lain ditransplantasikan di subkapsula ginjal pada mencit yang sama (autotransplantasi). Pada hari ke-19 pasca transplan, 5 ekor mencit disuntik PMSG dengan dos·1s 5 IU/ ekor untuk kelompok PMSG dan 5 ekor mencit tanpa disuntik PMSG untuk kelompok PMSG. Pada hari ke-21 pasca transplan (48 jam pasca penyuntikan PMSG), ovarium dikoleksi dan difiksasi untuk pemeriksaan histologi. Pengamatan · dilakukan terhadap morfologi ovarium dan jumlah folikel primordial, primer, sekunder, tersier dan corpus luteum (CL) yang memiliki morfologi normal. Hasil penelitian menunjukkan bahwa morfologi ovarium dan folikel pada mencit PMSG. lnduksi PMSG berpengaruh nyata terhadap peningkatan jumlah folikel tersier tetaRi tidak pada folikel tahap yang lain. Jumlah folikel tersier pada kelompok PMSG •> (23.8 ± 15.2) lebih tinggi jika dibandingkan dengan kelompok PMSG<·l (14.1 ± 8.0) dan berbeda nyata dibandingkan dengan ovarium sebelum transplantasi (8.5 ± 2.3) (P<0.05). Dari hasil ini dapat disimpulkan bahwa induksi PMSG mampu meningkatkan jumlah folikel tersier pada mencit yang mengalami autotransplantasi ovarium
Respons Optik dan Kinerja Penginderaan Indeks Bias Nanopartikel Perak Berlapis SiO2
No full textTelah dilakukan studi tentang respons optik nanopartikel perak berlapis SiO2 menggunakan metode aproksimasi kuasi-statik. Hasil studi menunjukkan bahwa spektrum efisiensi hamburan cahaya oleh nanopartikel sangat bergantung pada ketebalan lapisan SiO2 dan jari-jari nanopartikel perak. Pertambahan ketebalan SiO2 akan menyebabkan spektrum efisiensi hamburan cahaya mengalami pelebaran (broadening) dan bergeser ke arah panjang gelombang yang lebih besar (redshift) dengan nilai puncak efisiensi hamburan menurun secara eksponensial. Sebaliknya, pertambahan jari-jari nanopartikel perak akan menyebabkan spektrum efisiensi hamburan cahaya mengalami penyempitan dan bergeser ke arah panjang gelombang yang lebih kecil (blueshift) dengan nilai puncak efisiensi hamburan meningkat secara eksponensial. Selanjutnya, diperoleh pula bahwa panjang gelombang puncak spektrum efisiensi hamburan mengalami redshift secara linier akibat peningkatan indeks bias medium di sekitar nanopartikel. Hal ini mengindikasikan bahwa nanopartikel perak berlapis SiO2 berpotensi dalam aplikasi penginderaan indeks bias. Hasil perhitungan kinerja penginderaan indeks bias nanopartikel perak berlapis SiO2 memiliki sensitivitas sebesar 17 nm/RIU dengan nilai figure of merit(FOM) sebesar 6,789 104 RIU-1
Explosive indentation study of B4C-TiAlx composites fabricated by the dipping exothermic reaction process
No full textThe aim of this study is to fabricate a high volume fraction B4C-reinforced intermetallic matrix composite by the dipping exothermic reaction process and investigate the shock impact damage response of composites by explosive indentation experiment. It has been shown that the final microstructure of the dipping exothermic reaction process-fabricated composite can be tailored by treatment of the constituent powders and post heat treatment. The hardness and impact damage resistance of the fabricated composites were evaluated.This work is supported by grants (No. N62649-03-0007) from AROFE(US Army
Research Office Far-East). The author thanks Drs. J. W. McCauley of ARL, Sean Yu and
R. Olesinskiof AROFE
Increasing the Performance of Passive Communication with Ambient Light
No full textMost wireless communication technologies have been using the Radio Frequency (RF) spectrum for decades. Due to the popularity of the Internet of Things (IoT), the RF spectrum has started to become densely populated. Researchers have begun to explore other bands of the electromagnetic spectrum that can be utilized as a communication media. One of the promising choices is the visible light spectrum.Visible Light Communication (VLC) refers to the wireless communication technology that utilizes the visible light spectrum. This spectrum is thousands of times wider than the Radio Frequency (RF) spectrum and is license-free. In VLC, data is transmitted by turning a light source on and off. However, not every light source can be controlled. Passive light sources such as the sun provide an immense amount of light that can be used for wireless communication if we can develop ways to modulate them. One of the researches that use ambient light to create a wireless link is LuxLink. LuxLink uses liquid crystal shutters to control passive light sources and provides low energy, reliable, and flicker-free (safe) communication. This thesis addresses several problems that the current LuxLink system has.We present LuxLink+, an extension of LuxLink that provides two main improvements. Firstly, the data rate of the system is relatively low (80~bps). To increase the data rate, we provide a thorough analysis of the system’s bandwidth. Afterward, we modify the modulation technique, which increases the data rate to 1000~bps at a range of 1.5~m.Secondly, the system has a static data rate, which means that the system cannot adapt its data rate to changes in the environment. We implement a rate adaptation algorithm that can change its data rate accordingly. LuxLink+ improves the average throughput of the system by up to 85 percent compared to LuxLink.Electrical Engineering | Embedded System
Performance investigation of an integrated wind energy system for co-generation of power and hydrogen
No full textIn this paper, a wind turbine energy system is integrated with a hydrogen fuel cell and proton exchange membrane electrolyzer to provide electricity and heat to a community of households. Different cases for varying wind speeds are taken into consideration. Wind turbines meet the electricity demand when there is sufficient wind speed available. During high wind speeds, the excess electricity generated is supplied to the electrolyzer to produce hydrogen which is stored in a storage tank. It is later utilized in the fuel cell to provide electricity during periods of low wind speeds to overcome the shortage of electricity supply. The fuel cell operates during high demand conditions and provides electricity and heat for the residential application. The overall efficiency of the system is calculated at different wind speeds. The overall energy and exergy efficiencies at a wind speed 5 m/s are then found to be 20.2% and 21.2% respectively
Perancangan Sistem Kontrol Motor Kursi Roda Secara Nirkabel Berbasis ESP32
No full textKelumpuhan merupakan suatu keadaan dimana penderita mengalami pelemahan fungsi pada anggota tubuhnya sehingga penderita tidak bertenaga atau tidak menggerakkan anggota tubuh sebagaimana mestinya. Terdapat beberapa kondisi yang dapat mengakibatkan kelumpuhan, mulai dari penyakit seperti stroke hingga kecelakaan. Seseorang yang mengalami kelumpuhan sering kali memiliki permasalahan dalam hal mobilitas sehari-hari. Mereka memerlukan alat tambahan agar dapat beraktivitas, salah satunya adalah kursi roda. Hingga saat ini telah terdapat kursi roda elektrik yang dikendalikan dengan menggunakan joystrick. Akan tetapi penggunaan joystick belum dapat menjawab permasalahan dari seseorang yang mengalami kelumpuhan. Karena bagi orang yang mengalami kelumpuhan pada bagian lengan akan kesusahan dalam mengendalikan kursi roda elektrik berjenis ini. Pada penelitian ini telah dikembangkan kontroler kursi roda elektrik yang dapat digerakkan melalui teknologi visi komputer, baik dengan pose tangan maupun gestur kepala. Integrasi teknologi ini dapat menjadi solusi yang inovatif terhadap permasalahan yang sedang dihadapi. Pemilihan ESP32 sebagai mikrokontroler urama menjadi langkah strategis, karena kemampuanya dalam mengatur kerja motor dengan presisi. Selain berfungsi sebagai kontroler motor, ESP32 juga berperan sebagai perangkat penerima data dari komputer yang dilengkapi dengan teknologi visi komputer. Dari hasil pengujian, didapatkan suatu kesimpulan bahwa pengiriman dari visi komputer sebaiknya dikirim dalam bentuk JSON dan ditransmisikan menggunakan WiFi. Hal ini dilakukan karena transmisi data dalam bentuk JSON dan ditransmisikan melalui WiFi memiliki waktu delay yang terbaik, yaitu 1,032374783 detik. Melalui integrasi ini, diharapkan bahwa kontroler motor dapat beroperasi secara sinergis dengan informasi yang diterima dari komputer dan menciptakan sebuah sistem yang efisien dan responsif
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Paralysis is a condition where the sufferer experiences a weakening of the function of their body parts so that the sufferer has no strength or does not move their body parts as they should. There are several conditions that can cause paralysis, ranging from diseases such as stroke to accidents. Someone who experiences paralysis often has problems with daily mobility. They need additional equipment to be able to move, one of which is a wheelchair. Until now, there are electric wheelchairs that are controlled using a joystick. However, using a joystick cannot answer the problems of someone who is paralyzed. Because people who experience paralysis in their arms will have difficulty controlling this type of electric wheelchair. In this research, an electric wheelchair controller has been developed that can be moved using computer vision technology, both with hand poses and head gestures. The integration of this technology can be an innovative solution to the problems being faced. Choosing the ESP32 as the main microcontroller was a strategic step, because of its ability to regulate motor work with precision. Apart from functioning as a motor controller, the ESP32 also acts as a data receiving device from a computer equipped with computer vision technology. From the test results, it was concluded that computer vision transmissions should be sent in JSON form and transmitted using WiFi. This is done because data transmission in JSON form and transmitted via WiFi has the best delay time, namely 1.032374783 seconds. Through this integration, it is hoped that the motor controller can operate synergistically with the information received from the computer and create an efficient and responsive syste
Multigeneration system exergy analysis and thermal management of an industrial glassmaking process linked with a Cu–Cl cycle for hydrogen production
No full textA multigeneration system for hydrogen production linked with a glassmaking process via thermal management is examined in this study. The exhaust gas is interconnected with a Rankine cycle and the copper-chlorine (Cu–Cl) cycle for hydrogen production. The present system consists of a steam Rankine cycle, Cu–Cl cycle with multistage compression, double-stage organic Rankine cycle, and multi-effect desalination system. A Cu–Cl cycle based on the four-step model is employed with the proposed system. The useful system outputs are electricity, hydrogen, and fresh water. The simulation software packages utilized in the analysis and modeling are Engineering Equation Solver and Aspen Plus. The energy efficiency of the overall system is 36.5% while 38.1% is the exergy efficiency. The parametric studies are conducted to investigate the system performance. In addition, the effects of exhaust gas variables, such as flow rate, temperature, and pressure are examined to investigate the system performance
Leadership strategies for embedding sustainability and resilience in organizations with an emphasis on sustainable energy
No full textEfficient strategies to embedding sustainability in an organization are frequently linked to effective leadership. By design, changes in direction within an organization may lead to alterations in commitment or perceived significance of sustainability in organizations. While some organizational leaders are interested in embedding sustainability within a structure, other leaders believe in leaving the legacy behind and permanently influencing sustainability efforts. To confirm or dispel the underscored notion of the importance of leadership in embedding sustainability in organizations, a qualitative methodology approach to interviews, document analyses, and literature review is utilized. The research inquiry includes in-person interviews with top city staff and elected officials in a large Midwestern city and a review of the internal documents and reports. The end goal of the research is an examination of the role both elected and appointed officials have in embedding sustainability within cities, and whether a change in leadership may have an impact on continuity of sustainability implementation and
long-term viability of such policies. The paper focuses on the application of sustainable energy policies within a local government organizational structure as a mean of constructing a better understanding of leadership on sustainability implementation and embedment. While the further inquiry is needed, the research points out that an active partnership between city managers, administrators, and elected officials must be in place to support integrating sustainability from within and that sustainability thrives where exhaustive leadership support such
initiatives and efforts.Journal ArticleFinal article publishe
Measuring the Sustainability Impact in Local Governments Using the Quadruple Bottom Line
No full textSustainability is utilized by cities to enable a multifaceted, cross-sectoral approach for the betterment of communities and operational efficiency of organizations. Using a case study of the medium size local government in the Midwest and the city’s application of sustainability planning, this article focuses on a development of an expanded definition of the bottom line and a nascent approach to measuring and tracking sustainability-related efforts. The research provides an overview of measuring sustainability adopted by this particular city, using the target-specific,extended quadruple bottom line approach. The method attempts to address economic vitality, environmental quality, social equity, and governmental accountability through governance. The use of the quadruple bottom line to measure sustainability is linked to its annual budget planning and investments in transformation-related initiatives. While such an approach to measuring sustainability progress is unique in the United States, a number of cities in Australia have also adopted the quadruple bottom line approach to measure sustainability. Lessons in reporting sustainability efforts using the quadruple bottom line, in the context of an efficient and effective service delivery, can be applied to other local governments.Journal ArticleFinal article publishe
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