nils-herrmann/clean_scirepeval huggingface dataset:
Improving resolution and SNR of correlation function with the increase in bandwidth of recorded noise fields during estimation of bottom profile of ocean

Cross-correlation of coherent wave fronts of acoustic ambient noise fields gives an estimation of the bottom profile of ocean. Hydrophones are used to record the noise fields. Averaging time needed for estimating depth of sea bed depends on the number of coherent wave fronts extracted from the noise fields. In the current approach of depth estimation if only two hydrophones are used to record the acoustic noise fields, then it takes large amount of averaging time to extract sufficient amount of coherent wave fronts for estimating depth of sea bed. Use of a vertical array of hydrophones for noise field recording and later by combining the cross- correlation of all hydrophone pairs of the vertical array a stronger signature can be obtained and this greatly reduces averaging time. Reduction of averaging time can be expressed as increase in signal to noise ratio (SNR) and resolution of correlation function. Main goal of this paper is to increase SNR and resolution of correlation function using only two hydrophones and proper use of bandwidth of recorded noise fields. It is shown that recording large bandwidth signals in two hydrophones greatly increases SNR and resolution of correlation hence reduces the averaging time needed for estimating depth of sea bed. Results of this paper were verified using mathematical expression and simulation.
Estimation of speaker position using audio information

Real-time conversational video telecommunications services, such as video-conferencing, are becoming ever more important as a substitute for face-to-face meetings. One of the perceived weaknesses of existing services is the picture quality achieved, especially around the face of a speaker. A possible solution would be to identify the location of face, which is then transmitted at a higher quality than the rest of the picture. In this paper, we present a new technique for identifying the face using an array of microphones. As opposed to other techniques proposed so far, which make assumptions about the content of the video material, the idea relies on the estimation of lip position based on the audio processing from the speaker's speech. Once this estimation is performed, then a two or possibly three stage quantisation on video information will facilitate the compression of the subjectively more important parts, i.e. the face of a speaker with lower distortion. This new technique, which is compatible with all existing video compression standards, is much cheaper and easier to implement than previous techniques.
An adaptive search length algorithm for block matching motion estimation

This paper presents a new fast search algorithm for block matching motion estimation called the adaptive search length (ASL) algorithm. The ASL algorithm adaptively varies the number of positions searched for each block while still maintaining control of the average number of searches per block for each frame. Experimental results show that the peak signal-to-noise ratio (PSNR) of decoded sequences which were coded using the ASL algorithm is within 0.25 dB of the PSNR of decoded sequences which were coded using the full search block matching algorithm. It is also shown that the ASL algorithm requires only 10% of the computations required by the full search algorithm to achieve this level of decoded image quality.
Concealment for video communications over error-prone channels

Transmission of compressed video over error-prone channels requires techniques which are robust against errors and yet efficient in compressing the video. In this work, we study the use of concealment techniques for robust coding of video. We find that for sequences with irregular motion and changing scenes, a concealment technique which exploits both spatial information from the current frame and temporal information from the previous frame performs better than techniques which exploit only one of the sources of information.
Video error concealment using decoder motion vector estimation

Audio-visual and other multimedia services are seen as important sources of traffic for future wireless networks. An important characteristic of such networks is that they introduce a significant number of errors into the transmitted digital bitstream. For services' such as video, these errors can have the effect of degrading the quality of the received service to the point where it is unusable. We introduce a technique that allows the concealment of the impact of these errors. Our work is based on MPEG 2 encoded video (although our scheme would work equally well with other standards) to be transmitted over a wireless network whose data structures are similar to those of asynchronous transfer mode (ATM). Our simulations include the impact of the MPEG 2 Systems Layer and cover cell loss rates up to 5%.
Design of a Propagation-Delay-Tolerant MAC Protocol for Underwater Acoustic Sensor Networks

Underwater acoustic sensor networks (UASNs) can be employed in a vast range of applications, retrieving accurate and up-to-date information from underneath the ocean's surface. Although widely used by terrestrial sensor networks, radio frequencies (RFs) do not propagate well underwater. Therefore, acoustic channels are employed as an alternative to support long-distance and low-power communication in underwater sensor networks even though acoustic signals suffer from long propagation delay and have very limited bandwidth. In this paper, we introduce an adaptive propagation-delay-tolerant collision-avoidance protocol (APCAP) for the media access control (MAC) sublayer of UASN. The protocol includes an improved handshaking mechanism that improves efficiency and throughput in UASN where there is a large propagation delay. The mechanism guarantees nodes that can potentially interfere with a forthcoming transmission are properly informed. It also allows a node to utilize its idle time while waiting for messages to propagate, which is otherwise wasted by most existing MAC protocols. The simulation results indicate that where employed by UASN, APCAP exhibits good performance and outperforms the other MAC protocols examined in this paper.
Estimation by cross-correlation of the number of nodes in underwater networks

Knowledge of the number of nodes in a network is very useful in practical network operations. To date techniques employed to estimate the number of nodes in a network have been based on some aspect of the communications protocol(s) in use. Unfortunately, underwater networks have properties such as long propagation delay, high absorption, and dispersion that limit protocol-based techniques for estimating the number of nodes in a network. This paper investigates the estimation of the number of signal sources (N) in a region of interest through the cross-correlation of the acoustic signals received at two nodes. It is shown that the N can be expressed as a function of the mean and the standard deviation of the cross-correlation function. On the assumption that the signal sources are nodes in an underwater network, this method can be used to estimate the number of network nodes.
Robustness of multiplexing protocols for audio-visual services over wireless networks

The protocols used to multiplex the various streams in an audio-visual service (such as MPEG 2 systems and ITU-T H.223) have an important impact on the quality of the service. The fact that wireless channels are often associated with high bit-error rates which are often bursty means that the multiplexing protocols should be designed to be robust against such errors. We suggest two departures from traditional practice which can improve significantly the performance of a packet-oriented multiplex for use with audio-visual services: (1) where the packet header is protected against errors using forward error correcting codes, the use of a synchronization codeword (or flag) is often unnecessary, and (2) for channels where errors tend to occur in bursts, the occurrence of errors in the header can be reduced by transmitting the header information twice (at both ends of the packet) with a low level of FEC protection instead of using the same number of bits to obtain an increased level of protection using a single code word. The value of these approaches is confirmed by simulations.
Scalable video coding by stream morphing

Stream morphing is a new approach to scalable video coding similar in scope to those already included in the MPEG standards. It works by exploiting redundancy between a hierarchy of single layer bitstreams of increasing quality. This paper provides an overview of the technique along with results for the constant quantizer SNR scalable case which demonstrate good performance, especially for the class of "low motion" video sequences. In addition to SNR scalability, stream morphing has also been applied to temporal and spatial scalability.
A diversity-based scheme for reducing error propagation in video

We describe a robust codec for the transmission of very low bit-rate video over channels with bursty errors. The codec uses a diversity-based method in the form of multiple description codes to reduce the effect of errors in the video bit-stream. To improve the efficiency for transmission of very low bit-rate video, the codec also exploits adaptivity by only protecting macroblocks (using multiple description codes) which would otherwise be poorly concealed by the decoder. Simulations show significant improvements in the performance of the codec when compared to codecs which use intra macroblock updating (raster scan and random) with the same overhead for reducing the effects of errors.
Routing protocols for underwater ad hoc networks

Underwater wireless communications can enable many scientific, environmental and military applications. Because of the high attenuation and scattering effect of radio and optical waves respectively, underwater wireless communications are based on acoustic technology. The unique characteristics of the underwater medium - such as long propagation delay of the acoustic signal and extreme volatility of the link quality, poses unique challenges in the design of routing protocols for underwater acoustic sensor networks. In order to deal with this unreliable and unstable nature of the acoustic medium, authors in various literatures have proposed multi-hop data delivery routing schemes between the sources and the sink. However, these routing protocols are mostly dependent on the infrastructure of the underlying acoustic network making them unsuitable for pure ad hoc networks and hence limited in their applications. In this paper, we propose a routing protocol suitable for any kind of underwater acoustic sensor network, i.e. ad hoc networks. The protocol is generic in nature having traditional route discovery and route maintenance phase. The route maintenance phase is designed to reduce routing traffic. Simulation results show that the reduction of routing traffic improves the performance of the underlying acoustic network.
Low Bit-Rate Object-based Multi-view Video Coding using MVC

Work is currently underway to develop a new multi-view video coding (MVC) standard, based on the recent H.264/AVC standard. Recent work has shown, however, that object-based video coding can provide higher performance than H.264, especially at low bit rates and in sequences containing rotating camera motion and moving objects in the foreground. In this paper, we propose an object-based extension to MVC, in which sequences are segmented into foreground and background objects, with each object coded using H.264/AVC for single-view sequences and MVC for multi-view sequences. Experimental results show that the object-based approach significantly outperforms the basic MVC at low bit rates.
Quad-Tree Block-Based Binary Shape Coding

Shape masks are used in object-based video coding, such as MPEG-4 part 2, to specify the boundaries of a video object. The term ldquobinary shaperdquo is used to describe shape masks where each pixel is either completely inside the object or completely outside it, i.e., there is no blending of pixels at object boundaries. In this paper, we present a new lossless block-based coding algorithm for binary shapes that combines a quad-tree structure with context-based arithmetic coding. Experimental results demonstrate that this new approach provides a saving in bits generated up to approximately 66% compared to the MPEG-4 binary shape coding algorithm.
Motion-based object segmentation using local background sprites

It is well known that video material with a static background allows easier segmentation than that with a moving background. One approach to segmentation of sequences with a moving background is to use preprocessing to create a static background, after which conventional background subtraction techniques can be used for segmenting foreground objects. It has been recently shown that global motion estimation and/or background sprite generation techniques are reliable. We propose a new background modeling technique for object segmentation using local background sprite generation. Experimental results show the excellent performance of this new method compared to recent algorithms proposed.
Rare events and reverse-time models

Consideration is given to the estimation by simulation of probabilities of rare but potentially damaging events in Markovian systems. The problem is that the rarity of an event prevents its regular occurrence in simulation, and hence very long, time-consuming simulation runs are needed. It is shown how significantly faster estimates of the probabilities of rare events can be found by simulating a reverse-time model in place of the forward-time system. The simulation speedup afforded by simulating with the reverse-time model is compared with that obtained with alternative methods based on large deviations theory, using an uncontrolled Aloha system as an example.<<ETX>>
Texture feature extraction method for scale and rotation invariant image retrieval

In content-based image retrieval systems, the texture in the query image may appear at a different scale and rotation angle to the relevant images in the database. To overcome this limitation, proposed is a new method to extract features that are invariant to the scale and rotation of the texture in the image. The proposed method uses circular shifting in both the scale and the rotation dimensions in conjunction with a Gaussian window to reduce the effect of very high and very low frequencies in the feature matching process.
Visualisation of the terrain-sensitivity of radio communications

Planning for VHF and UHF communications has traditionally involved calculation of point-to-point radio-path losses using terrain data derived from a paper map. With the increased availability of digital terrain data, this process can be readily automated. The calculation of point-to-point losses, however, presents the user with limited information, and does not answer questions such as "if there is a transmitter located on that hill, over what area can receivers be located?" In this paper, we present a new approach based on area planning. This new approach generalises previously used point-to-point techniques, presenting a clear map overlay showing communications coverage from a user-selected transmitter location. Following the presentation of the algorithm, we present a number of cases in which misleading predictions of performance are given by point-to-point methods. Using the area-planning technique, we demonstrate how these misleading results arise.
Phase Based Disparity Estimation Using Adaptive Structured Light and Dual-Tree Complex Wavelet

In this paper, we propose a phase-based approach to estimate disparity between stereo images using the Dual-Tree Complex Wavelet transform and adaptive structured light. Firstly, a random noise adaptive structured light pattern is projected onto objects and two cameras capture stereo images. The adaptive colors are acquired using principle component analysis in the RGB color space of the image of the scene under ambient light to maximize the energy of the structured light and meanwhile minimize the energy of other noise factors. A Dual tree Complex Wavelet transform is then applied on the original three RGB channels of the scene under adaptive structured light and a fourth channel which mainly contains projected random noise generated using inverse principle component analysis. Finally the disparity map between the stereo images is generated by locating the minimum phase differences between left and right complex wavelet coefficients. Our experimental results show the proposed approach can generate high quality disparity maps.
Rate-distortion optimization for automatic sprite video coding using H.264/AVC

Sprite-based video coding offers higher compression efficiency than conventional block-based hybrid video coders. In sprite coding a sequence is divided into a model of its background, i.e. a so-called background sprite image, and a foreground object sequence. These are then encoded and transmitted to the receiver. At the decoder the output video sequence is synthesized using content previously transmitted. The background information of the video sequence is, other than the foreground object sequence, encoded indirectly, meaning for a sequence withN frames one single image is encoded and notN background frames. The background for a single frame is reconstructed by coordinate transformation at the decoder. An important issue to address here is an appropriate rate-distortion technique for optimization of the sprite-based coding approach, since foreground and background are encoded independently. In this paper, the Lagrangian cost function is considered for rate-constrained encoder control. Experimental evaluation shows the correct use of the optimization method and the gain in terms of rate-distortion performance compared to H.264/AVC.
A high data-rate, software-defined underwater acoustic modem

Most underwater acoustic modems offer only low data rates. This is largely because they operate at low frequency, which limits the channel bandwidth available, and hence the symbol rate. The low frequency acoustic channel suffers from substantial multipath and doppler effects, which constrain the signal quality at the receiver. As a result only 1 or 2 bits per symbol are achieved, with the effective data rate further reduced by error control coding. High frequency acoustic signals are heavily attenuated in water, severely constraining the range of high frequency links. High frequency signals however offer substantially greater signal bandwidth, and probably improved channel quality which guides our design choice of a high frequency acoustic modem for underwater communication.  Programmable Gate Arrays (FPGAs) can provide good system functionality at low cost and with the flexibility to perform rapid testing and development of communication algorithms. They may also be competitive in production systems. In this paper we describe current progress in development of a high frequency, high data-rate modem which is implemented entirely in FPGA. This differs from most existing modems which are based on DSP processors. Being software defined, the modem is flexible because the parameters can be reconfigured with relative ease, minimising the cost of rework as the design evolves. This modem will not only demonstrate the feasibility of high frequency FPGA based modems, but will also be a valuable tool to provide a better understanding of the high frequency acoustic channel, and demonstrate the utility of absorption to enhance channel re-use rates in underwater acoustic networks. The modulator has been implemented in the FPGA, to produce laboratory and open water tests that conform to modelling. The demodulator has been implemented in Matlab, and recovers the carrier, code synchronisation and data from recordings of both laboratory and open water tests. Coding of the demodulator into the FPGA is currently in progress.
Compressing Video for Networks - Optimized Coding in Resilient Framework

Although applications like transmission and sharing of multimedia are particularly attractive for many reasons, there are several factors, e.g. bandwidth, compression ratio or the important issue of unreliability of the transmission medium, that prohibit from gaining the most benefit of these applications. We describe in this paper a video codec for video transmission application. A resilient coding framework namely Multiple Description Coding (MDC) is used that guarantee improved quality video in lossy networks. An end-to-end optimization algorithm is also proposed to ensure good compression performance. Experimental evaluation in simulated network shows that the proposed codec achieves better reconstructed video quality compared to existing methods.
A Bio-inspired Host-Based Multi-engine Detection System with Sequential Pattern Recognition

In this paper, multiple detection engines with multi-layered intrusion detection mechanisms are proposed. The principle is to coordinate the results from each single-engine intrusion alert system, by seamlessly integrating with the multiple layered distributed service-oriented structure. An improved hidden Markov model (HMM) is created for the detection engine which is capable of the immunology-based self/nonself discrimination. The classifications of normal and abnormal behaviours of system calls are further examined by an advanced fuzzy-based inference process called HPSOWM. Considering a real benchmark dataset from the public domain, our experimental results show that the proposed scheme can greatly shorten the training time of HMM and reduce the false positive rate significantly. The proposed HPSOWM especially works for the efficient classification of unknown behaviors and malicious attacks.
On the Benefits of High Absorption in Practical Multi-hop Networks

Underwater acoustic communications in their present form do not appear to provide an ability to dramatically increase throughput or range at reasonable energy efficiency. Networks with a long, single-hop between nodes require a significant increase in power to increase throughput or range. Multi-hop networks at current operating frequencies offer improvements in energy efficiency or range, but with severe limits on throughput. We show that the throughput limitations of multi-hop networks with a shared channel can be overcome in a high absorption regime. Underwater acoustic absorption is a well behaved function of frequency, and extremely high absorptions can be accessed at useful frequencies so that network range and capacity may be dramatically improved in an affordable manner.
Divergent beam shaping for high data-rate underwater communications

High data rate underwater communication systems remain elusive. High frequency propagation combined with a frequency re-use appears to be a viable means to achieve high data rate underwater networks. However the required low-cost, high-frequency, omni-directional transducers with reasonable power handling capabilities do not exist. Small transducers cannot handle power, but large devices become directional at increasing frequency. Small transducers are also likely to be expensive because of manufacturing tolerances. We propose and investigate using a divergent reflector to transform a narrow beam into a donut shaped radiation pattern. The anticipated beamshape from a reflector is modelled using ray tracing techniques. A prototype reflector is then constructed and tested in still fresh water, showing the ability of a reflector to shape the reflected beam in an appropriate pattern. Testing on a spar buoy in salt water confirmed the signal is radiated laterally and provides a consistent signal even between typical floating platforms.