172 research outputs found
Local Visual Microphones: Improved Sound Extraction from Silent Video
Sound waves cause small vibrations in nearby objects. A few techniques exist
in the literature that can extract sound from video. In this paper we study
local vibration patterns at different image locations. We show that different
locations in the image vibrate differently. We carefully aggregate local
vibrations and produce a sound quality that improves state-of-the-art. We show
that local vibrations could have a time delay because sound waves take time to
travel through the air. We use this phenomenon to estimate sound direction. We
also present a novel algorithm that speeds up sound extraction by two to three
orders of magnitude and reaches real-time performance in a 20KHz video.Comment: Accepted to BMVC 201
On the performance of 1-level LDPC lattices
The low-density parity-check (LDPC) lattices perform very well in high
dimensions under generalized min-sum iterative decoding algorithm. In this work
we focus on 1-level LDPC lattices. We show that these lattices are the same as
lattices constructed based on Construction A and low-density lattice-code
(LDLC) lattices. In spite of having slightly lower coding gain, 1-level regular
LDPC lattices have remarkable performances. The lower complexity nature of the
decoding algorithm for these type of lattices allows us to run it for higher
dimensions easily. Our simulation results show that a 1-level LDPC lattice of
size 10000 can work as close as 1.1 dB at normalized error probability (NEP) of
.This can also be reported as 0.6 dB at symbol error rate (SER) of
with sum-product algorithm.Comment: 1 figure, submitted to IWCIT 201
Modeling transport of charged species in pore networks: solution of the Nernst-Planck equations coupled with fluid flow and charge conservation equations
A pore network modeling (PNM) framework for the simulation of transport of
charged species, such as ions, in porous media is presented. It includes the
Nernst-Planck (NP) equations for each charged species in the electrolytic
solution in addition to a charge conservation equation which relates the
species concentration to each other. Moreover, momentum and mass conservation
equations are adopted and there solution allows for the calculation of the
advective contribution to the transport in the NP equations.
The proposed framework is developed by first deriving the numerical model
equations (NMEs) corresponding to the partial differential equations (PDEs)
based on several different time and space discretization schemes, which are
compared to assess solutions accuracy. The derivation also considers various
charge conservation scenarios, which also have pros and cons in terms of speed
and accuracy. Ion transport problems in arbitrary pore networks were considered
and solved using both PNM and finite element method (FEM) solvers. Comparisons
showed an average deviation, in terms of ions concentration, between PNM and
FEM below with the PNM simulations being over times faster
than the FEM ones for a medium including about pores. The improved
accuracy is achieved by utilizing more accurate discretization schemes for both
the advective and migrative terms, adopted from the CFD literature. The NMEs
were implemented within the open-source package OpenPNM based on the iterative
Gummel algorithm with relaxation.
This work presents a comprehensive approach to modeling charged species
transport suitable for a wide range of applications from electrochemical
devices to nanoparticle movement in the subsurface
Fast object detection
The ultimate goal of computer vision is to understand images. We describe methods to understand images at two levels. One is at the level of description of images which we produce using sentences. These sentences talk about the things that are present in the image and about where they are and what they are doing. Then we ask in what ways should we describe images. We introduce visual phrases that are composite chunks of meaning. We show that object detectors could be better at detecting some visual phrases than detecting single objects.
This process of image understanding needs to use a lot of detectors. Running conventional object detectors at the rate required for image understanding could be very slow. We study fast object detection from an engineering perspective. We argue that a desirable object detector must: (1) be able to work with legacy templates; (2) be random access; (3) be able to trade accuracy versus speed; (4) have any-time property. We describe a method to have all of these features together for a fast detector. We apply these techniques to deformable parts model object detectors and show two orders of magnitude speed-up while adding their desirable features. We finally investigate the consequences of this architecture with a view of improving convolutional neural networks
Evaluating the performance of clarification and ultraviolet units in disinfection of Isfahan North waste water treatment plant (WWTP) effluent in pilot plant
زمینه و هدف: استفاده از پساب تصفیه خانه فاضلاب شهری به خصوص در مصارف کشاورزی مستلزم گندزدایی پساب تا حد استاندارد می باشد. کاربرد اشعه UV به دلیل معایب کمتر در مقایسه با سایر گندزداها، در نقاط مختلف دنیا در حال گسترش است. هدف از انجام این مطالعه بررسی امکان تصفیه و گندزدایی پساب تصفیه خانه فاضلاب شمال اصفهان با واحد زلال سازی و اشعه UV می باشد. روش بررسی: در این مطالعه تجربی از یک واحد زلال ساز و دو نوع سیستم گندزدایی فرابنفش کم فشار (LP) و فشار متوسط (MP) جهت گندزدایی پساب ثانویه استفاده شد. پارامترهای میکروبی کلیفرم کل و مدفوعی، استرپتوکوک مدفوعی و همچنین پارامترهای شیمیایی کل مواد معلق TSS (Total Suspended Solids)، آهن، سختی، جذب و عبور اشعه UV در نمونه های برداشت شده قبل و بعد از واحدها مورد آزمایش قرار گرفت. داده ها با استفاده از آزمون آماری t زوجی تجزیه و تحلیل گردید. یافته ها: متوسط عبور اشعهUV در طول موج nm254 (نانومتر) از پساب زلال شده 34 درصد و میزان جذب اشعهau/cm 47/0 بدست آمد. در گندزدایی پساب زلال شده توسط لامپ LP، MP و تلفیق هر دو نوع لامپ، به ترتیب در دوز اشعه 400، 576 و mws/cm2 407 (میلی وات ثانیه بر سانتی متر مربع) غلظت کلیفرمها به حد استاندارد سازمان حفاظت محیط زیست ایرانml) 100 FC/ 400 و TC1000 (رسید و تعداد استرپتوکوک مدفوعی در دوزهای mws/cm2400، 422 و mws/cm2407 تا log 5 کاهش یافت (05/0
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