Showing papers by "Gaurav Sharma published in 2009"

Development of real-world driving cycle: Case study of Pune, India

Abstract: The critical component of all emission models is a driving cycle representing the traffic behaviour. Although Indian driving cycles were developed to test the compliance of Indian vehicles to the relevant emission standards, they neglects higher speed and acceleration and assume all vehicle activities to be similar irrespective of heterogeneity in the traffic mix. Therefore, this study is an attempt to develop an urban driving cycle for estimating vehicular emissions and fuel consumption. The proposed methodology develops the driving cycle using micro-trips extracted from real-world data. The uniqueness of this methodology is that the driving cycle is constructed considering five important parameters of the time-space profile namely, the percentage acceleration, deceleration, idle, cruise, and the average speed. Therefore, this approach is expected to be a better representation of heterogeneous traffic behaviour. The driving cycle for the city of Pune in India is constructed using the proposed methodology and is compared with existing driving cycles.

MATLAB®: a language for parallel computing

Abstract: Parallel computing with the MATLAB® language and environment has received interest from various quarters. The Parallel Computing Toolbox™ and MATLAB® Distributed Computing Server™ from The MathWorks are among several available tools that offer this capability. We explore some of the key features of the parallel MATLAB language that these tools offer. We describe the underlying mechanics as well as the salient design decisions and rationale for certain features in the toolset. The paper concludes by identifying some issues that we must address as the language features evolve.

Performance Analysis of Contention Based Medium Access Control Protocols

Abstract: This paper studies the performance of contention based medium access control (MAC) protocols. In particular, a simple and accurate technique for estimating the throughput of the IEEE 802.11 DCF protocol is developed. The technique is based on a rigorous analysis of the Markov chain that corresponds to the time evolution of the back-off processes at the contending nodes. An extension of the technique is presented to handle the case where service differentiation is provided with the use of heterogeneous protocol parameters, as, for example, in IEEE 802.11e EDCA protocol. Our results provide new insights into the operation of such protocols. The techniques developed in the paper are applicable to a wide variety of contention based MAC protocols.

Wafer level embedding technology for 3D wafer level embedded package

Abstract: This paper presents the development of wafer level embedding process for a three dimensional (3D) embedded micro wafer level package (EMWLP). Wafer level embedding process was carried out by using compression molding machine and low-cost granular epoxy molding compound (EMC). Various molding process parameters such as molding time and temperature and three EMCs of different CTEs were analyzed to achieve reliable 3D EMWLP. Several molding process issues, such as warpage, die-sweep, EMC penetration, and die-shift, were faced during embedding process development. A large warpage of more than 1 mm and die-shift of more than 600 µm were found to occur in reconstructed molded wafer. Wafer level embedding process was optimized to reduce warpage and die-shift problems. A significant reduction in warpage (∼ 30 %) and die-shift (∼ 88 %) were achieved after embedding process optimization. The detail of process optimization is presented in the paper. Reconstructed molded wafers were subjected to various reliability tests, such as thermal cycle (TC), moisture sensitivity test-level 3 (MST-L3), and highly accelerated stress test (HAST). Scanning acoustic microscopy (SAM) analysis of molded wafers was carried out to analyze the void formation and delamination in molded wafers. No major void or delamination was observed in reconstructed wafer after molding as well as after reliability tests.

Geometric distortion signatures for printer identification

Abstract: We present a forensic technique for analyzing a printed image in order to trace the originating printer. Our method, which is applicable for commonly used electrophotographic (EP) printers, operates by exploiting the geometric distortion that these devices inevitably introduce in the printing process. In the proposed method, first a geometric distortion signature is estimated for an EP printer. This estimate is obtained using only the images printed on the printer and without access to the internal printer controls. Once a database of printer signatures is available, the printer utilized to print a test image is identified by computing the geometric distortion signature from test image and correlating the computes signatures against the printer signatures in the database. Experiments conducted over a corpus of EP printers demonstrate that the geometric distortion signatures of test documents exhibit high correlation with the corresponding printer signatures and a low correlation with other printer signatures. The method is therefore quite promising for forensic printer identification applications. We highlight several of the capabilities and challenges for the method.

Method for encoding and decoding data in a color barcode pattern

Abstract: What is disclosed is a system and method for encoding and decoding data in a color barcode pattern using dot orientation and color separability. The spectral (wavelength) characteristics of the CMY colorants, commonly used in digital printing, and those of RGB sensors are exploited to achieve high capacity data embedding rates in color barcodes. The present method embeds independent data in two different printer colorant channels using dot orientation modulation. In the print end, dots of two colorants occupy the same spatial region. At the detector end, by using the complementary sensor channels to estimate the colorant channels, data is recovered in each colorant channel. The method approximately doubles the capacity of encoding methods based upon a single colorant channel and enables embedding rates which match or exceed that of other hardcopy barcodes known in the arts. The method is robust against inter-separation misregistration with a small symbol error rate.

A novel method to predict die shift during compression molding in embedded wafer level package

Abstract: The increased functionality of cellular phones and handheld devices requires system level integration. Thus there is a strong demand in cell phone maker to move to embedded micro wafer level packaging (EMWLP). But the major problem encountered is die shift during compression molding. This paper presents a novel method to predict the die shift during wafer level molding process. A series of parametric studies are performed by changing the die thickness, die pitch distance and top mold chaste compression velocity. The effect of thinning down the chip thickness affects the pressure difference and local shear rate on the chip surfaces. The rate of change of epoxy mold compound fluid pressure across the die top surfaces is not constant. The local shear rate is increasing linearly from the centre of the wafer to the outermost die. From the parametric studies, the die shift is inversely proportional to the die thickness for wafer level molding. Such a phenomenon will reduce the lithography alignment error in the next process. This paper also shows that by reducing die pitch distance of a 5 × 5 mm2, 500 µm thick chip, the die shift decreases by a factor of 12%. In addition, the top mold chaste compression velocity contributes to the die shift by as much as 28% when the velocity is reduced by 50% from 100 µm/sec to 50 µm/sec Finally it is observed from experiment result that the die shift is not constant in all directions.

High capacity color barcodes using dot orientation and color separability

Abstract: Barcodes are widely utilized for embedding data in printed format to provide automated identification and tracking capabilities in a number of applications. In these applications, it is desirable to maximize the number of bits embedded per unit print area in order to either reduce the area requirements of the barcodes or to offer an increased payload, which in turn enlarges the class of applications for these barcodes. In this paper, we present a new high capacity color barcode. Our method operates by embedding independent data in two different printer colorant channels via halftone-dot orientation modulation. In the print, the dots of the two colorants occupy the same spatial region. At the detector, however, by using the complementary sensor channels to estimate the colorant channels we can recover the data in each individual colorant channel. The method therefore (approximately) doubles the capacity of encoding methods based on a single colorant channel and provides an embedding rate that is higher than other known barcode alternatives. The effectiveness of the proposed technique is demonstrated by experiments conducted on Xerographic printers. Data embedded at a high density by using the two cyan and yellow colorant channels for halftone dot orientation modulation is successfully recovered by using the red and blue channels for the detection, with an overall symbol error rate that is quite small.

Embedded wafer level packages with laterally placed and vertically stacked thin dies

Abstract: Two embedded micro wafer level packages (EMWLP) with (1) laterally placed and (2) vertically stacked thin dies are designed and developed. 3D stacking of thin dies is illustrated as progressive miniaturization driver for multi-chip EMWLP. Both the developed packages have dimensions of 10mm × 10mm × 0.4mm and solder ball pitch of 0.4mm. As part of the work several key processes like thin die stacking, 8 inch wafer encapsulation using compression molding, low temperature dielectric with processing temperature less than 200 °C have been developed. The developed EMWLP components successfully pass 1000 air to air thermal cycling (−40 to 125 °C), unbiased highly accelerated stress testing (HAST) and moisture sensitivity level (MSL3) tests. Developed EMWLP also show good board level TC (≫ 1000 cycles) and drop test reliability results. Integration of thin film passives like inductors and capacitors are also demonstrated on EMWLP platform. Developed thin film passives show a higher Q factor when compared to passives on high resistivity silicon platform. Thermo-mechanical simulation studies on developed EMWLP demonstrate that systemic control over die, RDL and package thicknesses can lead to designs with improved mechanical reliability.

Proline, catalase and root traits as indices of drought resistance in bold grained rice (Oryza sativa) genotypes

Abstract: The present experiment was carried out with 39 bold grained rice genotypes to study the genetic variability of the traits conferring drought resistance and to screen the drought tolerant rice genotypes with a view to formulate an efficient breeding programme for time bound genetic enhancement. The field experiment was grown during Sali season of 2007 to estimate the genetic variability of eight quantitative traits; root weight (g), number of primary roots, number of tillers/plant, root length (cm),shoot weight (g), root:shoot ratio by length and root:shoot ratio by weight. The data for the quantitative traits were recorded after 60 days of transplanting. The analysis of variance of eight quantitative traits revealed that there was significant genetic variation among the genotypes for the traits conferring drought resistance. The genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), heritability in broad sense (h2bs) and genetic advance (GA) as percent mean were estimated for all the eight quantitative traits. Small difference between GCV and PCV estimates was observed for shoot length (cm), root length (cm), number of primary roots, shoot weight (g), number of tillers/plant and root:shoot ratio by length suggesting that these characters were little influenced by environment and could be substantially improved through selection breeding program. Out of 39 rice genotypes, 7 genotypes including 2 checks (Ranjit and Monohar Sail) were selected on the basis of morphometric traits for drought resistance. Fifteen day old seedlings of seven selected rice genotypes were subjected to different osmotics of PEG-6000 (0.0, -0.4 and -0.8 MPa) to evaluate the effect of drought stress on proline, protein and antioxidant enzyme catalase. Poline content and catalase activity analyses further suggested that five selected bold grained rice genotypes (excluding two checks) namely Halodhar, George Sail, Kapili Dhan, Karmi Sail and Baodum were potentially drought tolerant.

Optimal Spread Spectrum Watermark Embedding via a Multistep Feasibility Formulation

Abstract: We consider optimal formulations of spread spectrum watermark embedding where the common requirements of watermarking, such as perceptual closeness of the watermarked image to the cover and detectability of the watermark in the presence of noise and compression, are posed as constraints while one metric pertaining to these requirements is optimized. We propose an algorithmic framework for solving these optimal embedding problems via a multistep feasibility approach that combines projections onto convex sets (POCS) based feasibility watermarking with a bisection parameter search for determining the optimum value of the objective function and the optimum watermarked image. The framework is general and can handle optimal watermark embedding problems with convex and quasi-convex formulations of watermark requirements with assured convergence to the global optimum. The proposed scheme is a natural extension of set-theoretic watermark design and provides a link between convex feasibility and optimization formulations for watermark embedding. We demonstrate a number of optimal watermark embeddings in the proposed framework corresponding to maximal robustness to additive noise, maximal robustness to compression, minimal frequency weighted perceptual distortion, and minimal watermark texture visibility. Experimental results demonstrate that the framework is effective in optimizing the desired characteristic while meeting the constraints. The results also highlight both anticipated and unanticipated competition between the common requirements for watermark embedding.

Stochastic sampling of the RNA structural alignment space

Abstract: A novel method is presented for predicting the common secondary structures and alignment of two homologous RNA sequences by sampling the ‘structural alignment’ space, i.e. the joint space of their alignments and common secondary structures. The structural alignment space is sampled according to a pseudo-Boltzmann distribution based on a pseudo-free energy change that combines base pairing probabilities from a thermodynamic model and alignment probabilities from a hidden Markov model. By virtue of the implicit comparative analysis between the two sequences, the method offers an improvement over single sequence sampling of the Boltzmann ensemble. A cluster analysis shows that the samples obtained from joint sampling of the structural alignment space cluster more closely than samples generated by the single sequence method. On average, the representative (centroid) structure and alignment of the most populated cluster in the sample of structures and alignments generated by joint sampling are more accurate than single sequence sampling and alignment based on sequence alone, respectively. The ‘best’ centroid structure that is closest to the known structure among all the centroids is, on average, more accurate than structure predictions of other methods. Additionally, cluster analysis identifies, on average, a few clusters, whose centroids can be presented as alternative candidates. The source code for the proposed method can be downloaded at http:// rna.urmc.rochester.edu.

Comparison of Flooding and Directed Diffusion for Wireless Sensor Network

Abstract: A Wireless Sensor Network (WSN) is a collection of thousands of tiny sensor nodes having the capability of wireless communication, limited computation and sensing. In this paper, all the components of a sensor node are discussed in brief. Also, a comparison of two routing protocols Flooding and Directed Dif- fusion on the basis of throughput, energy consumption and net- work lifetime is presented. Keywords-component; Wireless Sensor Networks; flooding; directed diffusion

Demonstration of high quality and low loss millimeter wave passives on embedded wafer level packaging platform (EMWLP)

Abstract: With the increasing demand for system integration to cater for continuously increasing I/Os as well as higher operating frequencies, EMWLP is emerging as a promising technology for integration. This platform allows integrated passives to be designed in the redistribution layers using the mold compound as a substrate, which significantly improves the passives performance compared to those of on-chip. In this paper, we present the results of high quality passives on EMWLP platform that are benchmarked against high resistivity silicon (HiRSi). The passives were then demonstrated in two band pass filters targeted to operate in the IEEE 802.11a band, with electrical performances comparable to that of commercial IPDs. Using the same platform, the measured loss characteristics of transmission lines up to 110 GHz is reported. We also demonstrate for the first time a low loss narrowband 77-GHz band pass filter on EMWLP platform, with a good correlation obtained between simulation and measurement results.

Device temporal forensics: An information theoretic approach

Abstract: By formulating the problem of ordering the outputs observed from a device over time, we pose a new problem in forensics and propose a framework for addressing this problem of device temporal forensics. Our proposed framework is based on a two-stage approach wherein time-dependent device parameters are first estimated from observed outputs and the resulting estimates are then temporally ordered by employing a Markov model for the temporal evolution of device parameters and exploiting the data processing inequality in information theory. We demonstrate and evaluate a simple realization of the framework for digital camera forensics based on photo-response non-uniformity. Results obtained over a database of online images indicate that the method provides accurate temporal ordering.

Continuous Phase-Modulated Halftones

Abstract: A generalization of periodic clustered-dot halftones is proposed, wherein the phase of the halftone spots is modulated using a secondary signal. The process is accomplished by using an analytic halftone threshold function that allows halftones to be generated with controlled phase variation in different regions of the printed page. The method can also be used to modulate the screen frequency, albeit with additional constraints. Visible artifacts are minimized/eliminated by ensuring the continuity of the modulation in phase. Limitations and capabilities of the method are analyzed through a quantitative model. The technique can be exploited for two applications that are presented in this paper: (a) embedding watermarks in the halftone image by encoding information in phase or in frequency and (b) modulating the screen frequency according to the frequency content of the continuous tone image in order to improve spatial and tonal rendering. Experimental performance is demonstrated for both applications.

Computational Studies of a Protein-based Nanoactuator for Nanogripping Applications

Abstract: The design hypothesis, architectures, and computational modeling of a novel peptide-based nanoactuator are presented in this paper. We engineered the I±-helical coiled-coil portion of the yeast transcriptional activator peptide called GCN4 to obtain an environmentally responsive nanoactuator. The dimeric coiled-coil peptide consists of two identical approximately 4.5 nm long and approximately 3 nm wide polypeptide chains. The actuation mechanism depends on the modification of electrostatic charges along the peptide by varying the pH of the solution resulting in the reversible movement of helices and, therefore, creating the motion of an actuator. Using molecular dynamics simulations we showed that pH changes led to a reversible opening of up to 1.5 nm which is approximately 150% of the initial separation of the nanoactuator. We also investigated the forces generated by the nanoactuator upon pH actuation, using a new method based on a modified steered molecular dynamics technique. Owing to its open and close motion resembling that of tweezers, the new nanoactuator can potentially be used as a nanogripper in various nanomanipulation tasks such as detection and removal of heavy metal ions during nanofabrication processes or as a molecular switch.

Thermal modeling and characterization of the embedded micro wafer level package (EMWLP) at the package- and system-level

Abstract: In this paper, package-level thermal modeling of the embedded micro-wafer-level-packaging (EMWLP) package has been performed to extract the parametric trends for thermal design guidelines of an eccentric single active die embedded alongside an integrated passive device (IPD), as shown in Fig.1 (with optional heat sink as a cooling solution). Exploratory thermal resistance modeling of an embedded two-die-stack has also been conducted. The effect of the mold compound used in the thermal models is further considered under the following parameters: mold thickness and thermal conductivity (0.4 W/mK to 2.5 W/mK). The effects of heat spreaders and heat sinks on the package thermal resistance are also studied, with due consideration paid to the above mold parameters. Furthermore, experimental characterization has been conducted to validate the package-level simulation for the single active die model, conforming to the JEDEC JESD 51-2A Thermal Measurements in Natural Convection standard. Finally, simulation results for a general system-level thermal modeling in both cellphone as well as laptop systems are also performed. Thermal management solutions for both scenarios, such as thermal vias and heat spreaders, are studied, with an optimal cooling solution proposed.

Optimized energy allocation in battery powered image sensor networks

Abstract: We investigate energy allocation strategies in image sensor networks for the purpose of maximizing the network operational lifetime. For the application scenarios that we consider, visual coverage over a monitored region is obtained by deploying wireless, battery-powered image sensors. Each sensor camera provides coverage over a part of the monitored region and a central processor coordinates the sensors in order to gather required visual data. We characterize the network lifetime as a stochastic random variable that depends upon the coverage geometry for the sensors and the distribution of data requests over the monitored region. Using this characterization we consider optimized strategies for energy allocation among the sensors that maximize the expected network lifetime. The formulation naturally leads to a max-min optimization problem that aims to maximize the duration of coverage for the most critical region for which the available energy is the least. We transform this problem into an equivalent linear programming problem, leading to a computationally efficient solution. The effectiveness of the proposed energy allocation strategy is validated by simulations.

Sensor scheduling for lifetime maximization in user-centric sensor networks

Abstract: We explore sensor scheduling strategies to maximize the operational lifetime of a user-centric image sensor network. Image sensors are deployed for gathering visual information over a monitored region. Users navigate within this region by specifying a time-varing desired viewpoint and the network responds with the requested visual data. By modeling the user's desired viewpoint in a probabilistic framework, we develop a stochastic formulation of the network lifetime and investigate the camera scheduling strategy that maximizes the expected value of network lifetime. By suitably abstracting the problem, we present a closed-form solution for the simplistic case when the monitored region is divided into two parts. Using asymptotic analysis, we then present a simple camera scheduling strategy for the general case that we conjecture to be optimal. Simulation results demonstrate a clear advantage of the proposed camera scheduling approach over previously considered alternatives.

Active management of third stage of labor: Assessment of standard of care in one of the training institute

Abstract: Objective: To find out the quality of service (standard steps of the procedures) incorporated in the active management of the third stage of labor (AMTSL) in Maternity Hospital, Thapathali, Kathmandu, Nepal. Methods: Prospective (single blind) study, where the (uninformed) service providers had no knowledge that they were being assessed of their performances regarding the proper conduct of the AMTSL, in randomly selected 325 laboring women during all shifts of the day by 4 interns who carefully documented the findings in pre prepared standard 3 month duration reference during in the year 2061/2062 (2004/2005) in Maternity Hospital Thapathali, Kathmandu, Nepal. Results: (Pre) loading of oxytocin was correctly done immediately when the women were seen to bear down at second stage of labor. In 99.5% of cases (irrespective of duty shift). In 5.8 % of cases, the oxytocin doses were different from standard 10 units. The possibility of second twin was not ruled out in 81.9% before the administration of 10 units of IM oxytocin. Moreover, the study that controlled cord traction was revealed or showed applied in 50% of the cases without confirming uterine contraction while counter traction to the uterus was given in most of the cases (98.5%) along with effective examination of the placenta for its completeness in 98.2 % cases. Conclusion: This study shows that improvement in the standard AMTSL practices is still needed in the training providing institution, which demand ensuring the absence of twin tactfully before giving IM oxytocin within 2 minutes invariably after the delivery of the babies and also in giving slight traction on to the umbilical cord gently during uterine contraction along with counter traction to the uterus. Key words: Active management of third stage of labor AMTSL, oxytocin, uterine massage. doi:10.3126/njog.v1i2.2394 N. J. Obstet. Gynaecol Vol. 1, No. 2, p. 28-30 Nov-Dec 2006

Q-SIFT: Efficient feature descriptors for distributed camera calibration

Abstract: We consider camera self-calibration, i.e. the estimation of parameters for camera sensors, in the setting of a visual sensor network where the sensors are distributed and energy-constrained. With the objective of reducing the communication burden and thereby maximizing network lifetime, we propose an energy-efficient approach for self-calibration where feature points are extracted locally at the cameras and efficient descriptions for these features are transmitted to a central processor that performs the self-calibration. Specifically, in this work we use reduced-dimensionality quantized approximations as efficient feature descriptors. The effectiveness of the proposed technique is validated through feature matching, and epipolar geometry estimation which enable self-calibration of the network.

Floral diversity and limnological studies in and around Dholbaha dam (Punjab Shivalik, India)

Abstract: A detailed study on the floral diversity and limnological parameters were carried out at Dholbaha dam, Punjab, India during 2002-04. The study area has a moist deciduous forest surrounding it. A total of 82 plant species, including 15 algaes, 6 pteridophytes, 1 gymnosperm and 60 angiosperms (13 trees, 8 shrubs, 4 climbe rs, 1 parasite, 9 herbs, 10 grasses and 15 aquatic & wetland vegetation) were recorded during the study period.

Collection of damselflies and dragonflies (Odonata : Insecta) in National Pusa collection, division of entomology, Indian Agricultural Research Institute, New Delhi, India

Abstract: The Division of Entomology was established in 1905 as one of the five major Divisions of the Imperial Agricultural Research Institute located at Pusa, Bihar, it moved to New Delhi in 1936. Faunistic surveys led to the establishment of the National Pusa Collection (NPC), one of the largest collections of its kind in the world. This collection houses more than half a million specimens of which 0.1 million comprising about 17,500 species are authentically identified. In that, 273 species of Zygoptera/damselflies (125 species: 10 families), Anisozygoptera (1 species: 1 family) and Anisoptera/dragonflies (147 species: 5 families) belongs to 16 families of order Odonata were studied during 2006-07. All the insects collection and specimens are well preserved and maintained in the National Pusa Collection. This vast collection of odonates species in one place, will provide grand opportunity and help to professional odonatologists/ researchers in their studies/reference. Approximately 6,000 species and subspecies belonging to 630 genera in 28 families are known from all over the world (Tsuda, 1991), out of which 499 species and subspecies of Odonata under 139 genera in 17 families, are represented in India (Prasad and Varshney, 1995). They are among the dominant invertebrate predators in any ecosystem. Being predators both at larval and adult stages, they play a significant role in the food chain of forest ecosystem. In addition, their value as indicators of quality of the biotope is being increasingly recognized.

Optimal resource allocation for wireless video sensors with power-rate-distortion model of imager

Abstract: We consider optimal resource allocation for wireless video sensors (WVSs), including the image sensor subsystem into the system analysis. By assigning a power-rate-distortion (P- R-D) characteristic for the image sensor, we build a comprehensive P-R-D framework for WVS optimization. Within the scope of the developed framework, we solve the problem of how to allocate power among the image sensor, compression, and transmission modules of a WVS, to achieve the optimal reconstructed video quality under power and rate constraints. To demonstrate the optimization method, we further establish a P-R-D model for an image sensor based on pixel level sigma-delta (ΣΔ) image sensor design. A P-R-D performance analysis for a WVS verifies that including the image sensor in the system optimization procedure can improve the overall video quality and prolong the life-time of the wireless video network.

Low temperature dielectric material for embedded micro wafer level packaging

Abstract: In this paper, we have developed the evaluation results of low cure temperature (less than 200 deg C) dielectric materials in terms of process ability and adhesion on SiN and mold compound substrates. The results showed that the low cure temperature dielectric materials have good adhesion on SiN and mold compound substrate. Integration of thin film passives like inductors, capacitors and band pass filters are also demonstrated on this mold compound wafer platform using electroplated Cu and low cure temperature dielectric material. Developed thin film passives on mold compound wafer platform have significantly improved the passives performances that are benchmarked against high resistivity silicon wafer (HiRSi). Reliability test vehicles are fabricated using Cu RDL, low cure temperature dielectric material and electroplated Cu UBM with SAC solder bump interconnects. A complete description of dielectric material evaluation for EMWLP, process development of thin film passive fabrication and multi-layer RDL integration on reconstructed mold compound wafer has been discussed.

Survival period in fatal road traffic accidents

Abstract: The intervals between injury and death in 450 fatalities after road accidents were analyzed and correlated with other data. Pedestrians were commonest group involved (28.7%) followed by occupants of cars (25.8%) and Motorcyclists (23.1%). In round figures, a third of series died with in half an hour, two third by 12 hours and three Quarter by 48 hours after accidents. Ninety percent of victims died with in one week. The pattern of survival time could be divided into three phases.There was an early steep decline the 38.4% dying during first half an hour and 40% with in one hour of accident. This was followed by longer stage during which rate of dying decreased progressively in logarithmic fashion. The cumulative tolls were 60.2% by 6 hours, 67.8% by 12 hours, 77.1%by 24 hours and 90% by 7 days. Between 7 to 14 days another 7% died.