Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 8

Search results for: Looped Karatsuba (LK)

8 Analytical Comparison of Conventional Algorithms with Vedic Algorithm for Digital Multiplier

Authors: Akhilesh G. Naik, Dipankar Pal


In today’s scenario, the complexity of digital signal processing (DSP) applications and various microcontroller architectures have been increasing to such an extent that the traditional approaches to multiplier design in most processors are becoming outdated for being comparatively slow. Modern processing applications require suitable pipelined approaches, and therefore, algorithms that are friendlier with pipelined architectures. Traditional algorithms like Wallace Tree, Radix-4 Booth, Radix-8 Booth, Dadda architectures have been proven to be comparatively slow for pipelined architectures. These architectures, therefore, need to be optimized or combined with other architectures amongst them to enhance its performances and to be made suitable for pipelined hardware/architectures. Recently, Vedic algorithm mathematically has proven to be efficient by appearing to be less complex and with fewer steps for its output establishment and have assumed renewed importance. This paper describes and shows how the Vedic algorithm can be better suited for pipelined architectures and also can be combined with traditional architectures and algorithms for enhancing its ability even further. In this paper, we also established that for complex applications on DSP and other microcontroller architectures, using Vedic approach for multiplication proves to be the best available and efficient option.

Keywords: Wallace Tree, Radix-4 Booth, Radix-8 Booth, Dadda, Vedic, Single-Stage Karatsuba (SSK), Looped Karatsuba (LK)

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7 Very Large Scale Integration Architecture of Finite Impulse Response Filter Implementation Using Retiming Technique

Authors: S. Jalaja, A. M. Vijaya Prakash


Recursive combination of an algorithm based on Karatsuba multiplication is exploited to design a generalized transpose and parallel Finite Impulse Response (FIR) Filter. Mid-range Karatsuba multiplication and Carry Save adder based on Karatsuba multiplication reduce time complexity for higher order multiplication implemented up to n-bit. As a result, we design modified N-tap Transpose and Parallel Symmetric FIR Filter Structure using Karatsuba algorithm. The mathematical formulation of the FFA Filter is derived. The proposed architecture involves significantly less area delay product (APD) then the existing block implementation. By adopting retiming technique, hardware cost is reduced further. The filter architecture is designed by using 90 nm technology library and is implemented by using cadence EDA Tool. The synthesized result shows better performance for different word length and block size. The design achieves switching activity reduction and low power consumption by applying with and without retiming for different combination of the circuit. The proposed structure achieves more than a half of the power reduction by adopting with and without retiming techniques compared to the earlier design structure. As a proof of the concept for block size 16 and filter length 64 for CKA method, it achieves a 51% as well as 70% less power by applying retiming technique, and for CSA method it achieves a 57% as well as 77% less power by applying retiming technique compared to the previously proposed design.

Keywords: carry save adder Karatsuba multiplication, mid range Karatsuba multiplication, modified FFA and transposed filter, retiming

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6 Scalable Systolic Multiplier over Binary Extension Fields Based on Two-Level Karatsuba Decomposition

Authors: Chiou-Yng Lee, Wen-Yo Lee, Chieh-Tsai Wu, Cheng-Chen Yang


Shifted polynomial basis (SPB) is a variation of polynomial basis representation. SPB has potential for efficient bit-level and digit-level implementations of multiplication over binary extension fields with subquadratic space complexity. For efficient implementation of pairing computation with large finite fields, this paper presents a new SPB multiplication algorithm based on Karatsuba schemes, and used that to derive a novel scalable multiplier architecture. Analytical results show that the proposed multiplier provides a trade-off between space and time complexities. Our proposed multiplier is modular, regular, and suitable for very-large-scale integration (VLSI) implementations. It involves less area complexity compared to the multipliers based on traditional decomposition methods. It is therefore, more suitable for efficient hardware implementation of pairing based cryptography and elliptic curve cryptography (ECC) in constraint driven applications.

Keywords: digit-serial systolic multiplier, elliptic curve cryptography (ECC), Karatsuba algorithm (KA), shifted polynomial basis (SPB), pairing computation

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5 Finite Volume Method in Loop Network in Hydraulic Transient

Authors: Hossain Samani, Mohammad Ehteram


In this paper, we consider finite volume method (FVM) in water hammer. We will simulate these techniques on a looped network with complex boundary conditions. After comparing methods, we see the FVM method as the best method. We compare the results of FVM with experimental data. Finite volume using staggered grid is applied for solving water hammer equations.

Keywords: hydraulic transient, water hammer, interpolation, non-liner interpolation

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4 Studies on Influence of Rub on Vibration Signature of Rotating Machines

Authors: K. N. Umesh, K. S. Srinivasan


The influence of rotor rub was studied with respect to light rub and heavy rub conditions. The investigations were carried out for both below and above critical speeds. The time domain waveform has revealed truncation of the waveform during rubbing conditions. The quantum of rubbing has been indicated by the quantum of truncation. The orbits for light rub have indicated a single loop whereas for heavy rub multi looped orbits have been observed. In the heavy rub condition above critical speed both sub harmonics and super harmonics are exhibited. The orbit precess in a direction opposite to the direction of the rotation of the rotor. When the rubbing was created above the critical speed the orbit shape was of '8' shape indicating the rotor instability. Super-harmonics and sub-harmonics of vibration signals have been observed for light rub and heavy rub conditions and for speeds above critical.

Keywords: rotor rub, orbital analysis, frequency analysis, vibration signatures

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3 Performance Evaluations of Lap Spliced Joint of Decked Bulb-Tee Type Modular Bridge

Authors: Sang-Yoon Lee, Jae-Joon Song


Precast decked bulb-tee girder or precast deck generally adopts in-situ connections of loop joints. Loop joint could be an effective method to connect precast concrete members where the width of joint is not wide sufficiently to allow the lap splice length of reinforcing bars. However, the regulation for the minimum bend diameter of looped rebar gives limitation not to reduce the thickness of precast concrete member; thus, in-situ connection adopting loop joint place a constraint on improving the structural efficiency of precast concrete member. Ultra high strength concrete (UHSC) is effective on reduce the development and lap splice length of reinforcing bar. In-situ connection with UHSC gives a merit to reduce connection width. This study intends to investigate the details of the longitudinal joint to be applied in the precast modular bridge using decked bulb-tee girder that has been recently developed in Korea. This paper presents the details applying UHSC and lap splices of straight reinforcement and results of tests. Several tests were performed on flexural specimens with longitudinal joints to verify the length of the lap splices and amount of transverse reinforcement, and to examine the flexural strength of the longitudinal joint.

Keywords: precast structure, decked bulb-tee girder, in-situ connection, UHSC, modular bridge

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2 Architectural Wind Data Maps Using an Array of Wireless Connected Anemometers

Authors: D. Serero, L. Couton, J. D. Parisse, R. Leroy


In urban planning, an increasing number of cities require wind analysis to verify comfort of public spaces and around buildings. These studies are made using computer fluid dynamic simulation (CFD). However, this technique is often based on wind information taken from meteorological stations located at several kilometers of the spot of analysis. The approximated input data on project surroundings produces unprecise results for this type of analysis. They can only be used to get general behavior of wind in a zone but not to evaluate precise wind speed. This paper presents another approach to this problem, based on collecting wind data and generating an urban wind cartography using connected ultrasound anemometers. They are wireless devices that send immediate data on wind to a remote server. Assembled in array, these devices generate geo-localized data on wind such as speed, temperature, pressure and allow us to compare wind behavior on a specific site or building. These Netatmo-type anemometers communicate by wifi with central equipment, which shares data acquired by a wide variety of devices such as wind speed, indoor and outdoor temperature, rainfall, and sunshine. Beside its precision, this method extracts geo-localized data on any type of site that can be feedback looped in the architectural design of a building or a public place. Furthermore, this method allows a precise calibration of a virtual wind tunnel using numerical aeraulic simulations (like STAR CCM + software) and then to develop the complete volumetric model of wind behavior over a roof area or an entire city block. The paper showcases connected ultrasonic anemometers, which were implanted for an 18 months survey on four study sites in the Grand Paris region. This case study focuses on Paris as an urban environment with multiple historical layers whose diversity of typology and buildings allows considering different ways of capturing wind energy. The objective of this approach is to categorize the different types of wind in urban areas. This, particularly the identification of the minimum and maximum wind spectrum, helps define the choice and performance of wind energy capturing devices that could be implanted there. The localization on the roof of a building, the type of wind, the altimetry of the device in relation to the levels of the roofs, the potential nuisances generated. The method allows identifying the characteristics of wind turbines in order to maximize their performance in an urban site with turbulent wind.

Keywords: computer fluid dynamic simulation in urban environment, wind energy harvesting devices, net-zero energy building, urban wind behavior simulation, advanced building skin design methodology

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1 Inguinal Hernia Preperitoneal Mesh and Internal Hernia with Caecal Volvulus

Authors: Daniel Tani, Goutham Sivasuthan, Reuben Ndegwa, Omar Mansour


We report a case of a caecal volvulus in a 52-year-old female who had an internal hernia from adhesions originating at the region of a previous inguinal hernia mesh repair. The patient described epigastric and right lower quadrant pain for the preceding two weeks that seemed to worsen with oral intake. She had previous laparoscopic preperitoneal hernia repairs with mesh bilaterally; the left in 2007 and the right in 2012. Further surgical history included an open Spigelian hernia repair with mesh in the left lower quadrant and a laparoscopic cholecystectomy 20 years earlier. In addition to this, she had had a colonoscopy done three months prior, which showed no masses or polyps. The patient was hemodynamically stable on review with a soft abdomen. The right lower quadrant was exquisitely tender with a rebound. There were no palpable masses. Blood tests revealed hemoglobin of 155 g/L, a white cell count of 8 x 109/L, and a C-reactive protein of 37 mg/L. A computed tomography scan with portal venous contrast demonstrated a mechanical small bowel obstruction with the terminal ileum and caecum looped around itself in a whirlpool appearance, and the colon collapsed distally. There was a trace of free fluid in the right paracolic gutter and no abdominal free air. Hernia meshes were visible in the inguinal orifices bilaterally and at the left lower quadrant. The mesh on the right inguinal canal appeared to be displaced intraperitoneally. The patient then underwent emergency diagnostic laparoscopy. Intraoperatively, there was a caecal volvulus caused by internal herniation underneath a thick band adhesion at the right iliac fossa. This band appeared to arise from the anterior abdominal wall just posterior to the right inguinal hernia preperitoneal mesh. There was no mesh or tacks exposed and there was no recurrent hernia. A right hemicolectomy was performed with a stapled side-to-side anastomosis. The postoperative course was uncomplicated, and she was discharged on day 6. At follow-up two weeks later, the patient was well and bowel function had returned to normal. Histopathology was negative for dysplasia or malignancy. Inguinal preperitoneal mesh has not been definitively linked to intraabdominal adhesion formation. There has been a study in 2016 that examined the formation of adhesions after ventral hernia repair as detected by MRI and laparoscopic correlation. However, this included intraperitoneal mesh, and the results were not stratified by mesh location. There was an overall 60% rate of adhesions after ventral hernia mesh. There has also been one case report in the literature that describes an adhesional small bowel obstruction that was attributed to a tack that had been placed during a laparoscopic inguinal hernia repair. In our case report, there was clearly a band adhesion from the preperitoneal mesh that had led to an internal hernia and caecal volvulus; however, whether the mesh had initiated the adhesion is uncertain. While inguinal hernia repair with mesh remains the gold standard, the formation of intra-abdominal adhesions may need to be a consideration in fixation techniques.

Keywords: internal hernia, inguinal hernia mesh, caecal volvulus, adhesion

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