다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Most numerical integration techniques consist of approximating the integrand by a polynomial in a region or regions and then integrating the polynomial exactly. Often a complicated integrand can be factored into a non-negative ''weight'' function and another function better approximated by a polynomial, thus $\int_{a}^{b} g(t)dt = \int_{a}^{b} \omega (t)f(t)dt \approx \sum_{i=1}^{N} w_i f(t_i)$. Hopefully, the quadrature rule ${\{w_j, t_j\}}_{j=1}^{N}$ corresponding to the weight function $\omega$(t) is available in tabulated form, but more likely it is not. We present here two algorithms for generating the Gaussian quadrature rule defined by the weight function when: a) the three term recurrence relation is known for the orthogonal polynomials generated by $\omega$(t), and b) the moments of the weight function are known or can be calculated.

Calculation of Gauss quadrature rules.

Mobile data traffic will continue its tremendous growth in some markets, and has already resulted in an apparent radio spectrum scarcity. There is a strong need for more efficient methods to use spectrum resources, leading to extensive research on increasing spectrum reusability on flexible radio platforms. This study solves this problem in two sub topics, millimeter wave communication on wireless backhaul for spectrum reusability, and flexible prototyping radio platform using software-defined radio (SDR).
Wireless backhaul has received significant attention as a key technology affecting the development of future wireless cellular networks because it helps to easily deploy many small size cells, an essential part of a high capacity system. Millimeter wave is considered a possible candidate for cost-effective wireless backhaul. In the outdoor deployment using a millimeter wave, beamforming methods are key techniques to establish wireless links in the 60 GHz to 80 GHz to overcome pathloss constraints (i.e., rainfall effect and oxygen absorption). The millimeter wave communication system cannot directly access the channel knowledge. To overcome this, a beamforming method based on codebook search is considered. The millimeter wave communication cannot access channel knowledge, therefore alternatively a beamforming method based on a codebook search is considered. In the first part, we propose an efficient beam alignment technique using adaptive subspace sampling and hierarchical beam codebooks. A wind sway analysis is presented to establish a notion of beam coherence time. This highlights a previously unexplored tradeoff between array size and wind-induced movement. Generally, it is not possible to use larger arrays without risking a performance loss from wind-induced beam misalignment. The performance of the proposed alignment technique is analyzed and compared with other search and alignment methods. Results show significant performance improvement with reduced search time.
In the second part of this study, SDR is discussed as an approach toward flexible wireless communication systems. Most layers of SDR are implemented by software. Therefore, only a software change is needed to transform the type of radio system. The translation of the signal processing into software performed by a regular computer opens up a huge number of possibilities at a reasonable price and effort. SDR systems are widely used to build prototypes, saving time and money. In this project, a robust wireless communication system in high interference environment was developed. For the physical layer (PHY) of the system, we implemented a channel sub-bandding method that utilizes frequency division multiplexing to avoid interference. Then, to overcome a further interfered channel, Direct Spread Spectrum System (DSSS) was considered and implemented. These prototyped testbeds were evaluated for system performance in the interference environment.

Millimeter wave beamforming for wireless backhaul and access in small cell networks and practical approaches in software-defined radio

Recently, a millimeter‐wave band channel model for fifth generation and beyond communications, called fluctuating two‐ray (FTR) model, has been introduced, which accurately tracks the beha...

Performance of maximum ratio combining of fluctuating two‐ray (FTR) mmWave channels for 5G and beyond communications

Herein a theory of characteristic mode (TCM)-based design of circularly-polarized (CP) quad-band compact microstrip antenna is proposed. It involves one annular ring radiator having eight symmetrical slots along its boundary and three circular closed ring resonators (CRRs) on the bottom side of the substrate. Initially, CM analysis was carried out for the radiator without a feeding structure, to determine the modal currents and their corresponding modal fields (radiation patterns) of existing modes. This helped in recognizing the symmetric modes to be selectively excited by the feed to furnish CP and gave direction for selecting an asymmetric CPW-fed structure as the feed of choice. Evolution process of the antenna geometry shows that the eight symmetrical slots in tandem with the CRRs generate wide impedance bandwidth (IBW), while measured quad CP bands are obtained through uses of an asymmetric ground plane resonating at 5.63 GHz (120 MHz), a cross-shaped slit at 7.69 GHz (650 MHz), a rectangular open loop at 9.91 GHz (1200 MHz), and a tuning stub in the feeding structure at 12.09 GHz (160 MHz). Series of parasitic strips augmented CP radiation and eliminate ripples in the radiation pattern. Measured findings relate satisfactorily with simulations done using Ansys HFSS 2020 R1. A low cost FR-4 substrate is used to fabricate the antenna with an optimized dimension of 35 × 30 × 1.6 mm3. The measured IBW ranges from 4.36–4.82 GHz, 5.50–5.78 GHz, and 5.95–beyond 14 GHz. The proposed antenna may find suitable applications in C band, X band, and 5GHz WLAN devices.

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A Circularly Polarized Quad-Band Annular Ring Antenna with Asymmetric Ground Plane Using Theory of Characteristic Modes

Performance analysis of spatial modulation over generalized α−κ−μ fading distribution

Performance analysis of beamforming aided uncorrelated mm-Wave MIMO system for IEEE 802.15.3c standard

In this paper, We derived an expression of the average bit error rate (ABER) of the relay assisted two-hop ultra-wideband (UWB) communication system over IEEE 802.15.3a channel model incorporated with the transmit antenna selection at the source and relay nodes. In this two-hop system, each node equipped with the multiple antennas and relay is configured to perform decode and forward protocol. The analysis considers the numerically evaluated characteristic function of the sum of the path gains, which are specified in the IEEE 802.15.3a channel model. During the analysis, we assumed that all the channel links and channel paths are independent and identically distributed. Our result shows the derived ABER is well matched to the simulation. It also presents the comparison of the ABER between the investigated and the conventional UWB systems. This paper also presents the flowchart of the Monte-Carlo simulation of the investigated UWB system.

Transmit Antenna Selection in the Cooperative Communication Based UWB System

In this paper, we calculate the bit error rate (BER) of the ultra-wide band (UWB) wireless communication system over IEEE 802.15.3a channel model by superseding the lognormal (LN) shadow fading distribution to the Mixture of Gamma (MG) distributions. In general, shadow fading is the effect of random fluctuation of received signal power around the mean path loss and it is modeled as LN distribution. In this work, we approximate the LN shadow fading distribution to the MG distributions, because of intractable, indefinite mathematical expression of the characteristic function (CF) and moment generating function (MGF) of the LN distribution, which are required to evaluate BER of the UWB communication system. To estimate the approximate MG distributions parameters, we use rth moment algorithm with least square non-linear curve fitting criteria. This work employs the L-fingers RAKE receiver which is needed to collect the total energy at the receiver in the UWB system. The results show that 5-MG distributions is the good fit for LN shadow fading distribution of the UWB communication system. The proposed analytical BER is closely matched to the simulated BER for all the four IEEE 802.15.3a channel models. It verifies the accuracy of the approximation considered in this BER analysis.

Analysis of UWB communication over IEEE 802.15.3a channel by superseding lognormal shadowing by Mixture of Gamma distributions

The evolution of artificial intelligence has served as the catalyst in the field of technology and is making our imaginations real. One of such creation is the birth of self- driving car (autonomous robot). In this paper, a self-driving car physical prototype based on traditional visual method of lane keeping, implemented on Raspberry Pi is proposed which is capable of maneuvering on various kind of tracks autonomously. The proposed method comprises of taking an image from a front facing dashboard camera of the car, detecting the lane from the image and analysing the deviation of the car from the road which is further used to keep the car on the track. The proposed method is implemented on a 1/10 scale car which contains Raspberry Pi 3 Model-B computer and Pi Cam Rev 1.3 for computations and processing. The testing was done without any human intervention on self-made lined track having all kind of turns. The experimental results demonstrate the effectiveness and the robustness of the self-driving car in terms of the navigation error while following the reference trajectory.

Anand Agrawal

Papers

Performance analysis of spatial modulation over generalized α−κ−μ fading distribution

Performance analysis of beamforming aided uncorrelated mm-Wave MIMO system for IEEE 802.15.3c standard

Transmit Antenna Selection in the Cooperative Communication Based UWB System

Analysis of UWB communication over IEEE 802.15.3a channel by superseding lognormal shadowing by Mixture of Gamma distributions

Vision-based outdoor navigation of self-driving car using lane detection