Low-Power Folded Tree Architecture for DSP Applications

Low-Power Folded Tree Architecture for DSP Applications Low-Power Folded Tree Architecture for DSP applications Abstract— Wireless communication exhibits the highest energy consumption in wireless sensor network (WSN) nodes. Due to their limited energy supply from batteries, the low power design have become inevitable part of today’s wireless devices. Power has become a burning issue in VLSI design. In modern integrated circuits, the power consumed by clocking gradually takes a dominant part. Reducing the power consumption not only enhance battery life but also avoid overheating problem. By employing a more appropriate Processing Element (PE), the power consumption is significantly reduced. In this paper the novel method for low power design is achieved by using Folded Tree Architecture (FTA) and high speed adder design for on-the-node data processing in wireless sensor networks using Parallel Prefix Operations (PPO) and data locality in hardware. Besides power reduction the objective of minimizing area and delay is also considered. Index Terms— Folded Tree Architecture (FTA), Parallel Prefix Operation (PPO), Processing Element (PE), Wireless Sensor Network (WSN). INTRODUCTION Power optimization is always one of the most important design objectives in modern nanometer integrated circuit design. Especially for wireless sensor networks (WSNs), power optimization have become inevitable part in today VLSI design. Power optimization not only can enhance battery life but also reduce the overheating problem. Self-configuring wireless sensor networks can be invaluable in many civil and military applications for collecting, processing, and disseminating wide ranges of complex environmental data. Because of this, they have attracted considerable research attention in last years. Sensor nodes are battery driven and hence operate on an extremely frugal energy budget. Further, they must have a lifetime on the order of months to years. Since battery replacement is not an option for networks with thousands of physically embedded nodes. In some cases, these networks may be required to operate solely on energy scavenged from the environment through seismic, photovoltaic or thermal conversion. This transforms energy consumption into the most important factor that determines sensor node lifetime. The another important application in wireless sensor networks is event tracking, which has widespread use in applications such as security surveillance and wildlife habitat monitoring. Tracking involves a significant amount of collaboration between individual sensors to perform complex signal processing algorithms such as kalman filtering, Bayesian data fusion and coherent beamforming. This applications will require more energy for their processing. In general Wireless Sensor Networks (WSNs) can operate in four distinct mode of operation: Transmit, Receive, Idle and Sleep. An important observation in the case of most radios is that operating in Idle mode results in significantly high power consumption, almost equal to the power consumed in the Receive mode. The data-driven nature of WSN applications requires a specific low power data processing approach. By employing more appropriate Processing Element (PE), the power consumption in all the four mode of operation will be reduced significantly. In present VLSI technology, reducing power consumption is an important issue. Especially for WSN, due to their limited battery lifetime the low power VLSI design is become inevitable for wireless commmunication. The goal of this paper is to design an low-energy Folded Tree and Multi-Bit Flip-Flop Merging technique for WSN nodes. II. RELATED WORKS In paper [2], the author proposed low-energy data processing architecture for WSN nodes using folded tree method. This paper identifies that many WSN applications employ algorithms which can be solved by using parallel prefix-sums. Therefore, an alternative architecture is proposed to calculated them energy-efficiently. It consists of several parallel Processing Elements (PEs) structured as a folded tree. The folded tree method with parallel prefix operations reduces the number of processing element and memory bottleneck. Due to clock distribution for more flip-flops, it consumes more clock power and also parallel prefix operations has high delay. In paper [3], a novel method is proposed for low clock power consumption in WSN nodes. A previously derived clock energy model is briefly reviewed while a comprehensive framework for the estimation of system wide (chip level) and clock sub-system power as function of technology scaling is presented. This framework is used to study and quantify the impact that various intensifying concerns associated with scaling will have on clock energy and their relative impact on the overall system energy. This technology scaling method reduces power clock power consumption (both static and dynamic), but due to large number of processing element- area, inverter chain, Power-Delay Product is increased. III. PROPOSED SCHEME Folded Tree Architecture with Parallel Prefix Operation is used to reduce the total number of Processing Elements (PEs) in the VLSI design. By reducing the number of processing elements, the total area is reduced. Area is proportional to power, so power consumption is also reduced. During processing and transmission of signals, the WSN nodes will consume more power. Especially for clock distribution nearly 70% power will be consumed. In order to optimize the power during clock distribution, multi-bit flip-flop merging technique is used. A. Folded Tree Architecture A straightforward binary tree implementation of Blelloch’s approach costs a significant amount of area as n inputs require p = n − 1 PEs. To reduce area and power, pipelining can be traded for throughput. With a classic binary tree, as soon as a layer of PEs finishes processing, the results are passed on and new calculations can already recommence independently [8]. Fig 1. Binary tree equivalent to folded tree The idea presented here is to fold the tree back onto itself to maximally reuse the PEs. In doing so, p becomes proportional to n/2 and the area is cut in half. Area is proportional to power, so power is also cut in half. Note that also the interconnect is reduced. This folded tree topology is depicted in Fig. 1, which is functionally equivalent to the binary tree on the left. By using the Folded Tree architecture power consumption, area and wirelength is reduced considerably. Folded Tree Architecture (FTA) for on-the-node data processing in wireless sensor networks, using parallel preà ¯Ã‚ ¬Ã‚ x operations and data locality in hardware reduces both area and power consumption. TABLE I LEAKAGE POWER AND DYNAMIC ENERGY FOR ONE PE UNDER NORMAL CONDITIONS FTA is designed to reuse the PE nodes to reduces half of the total area. It limiting the data set by preprocessing with parallel preà ¯Ã‚ ¬Ã‚ x operations. The combination of data à ¯Ã‚ ¬Ã¢â‚¬Å¡ow and control à ¯Ã‚ ¬Ã¢â‚¬Å¡ow elements to introduce a local distributed memory, which removes the memory bottleneck while retaining sufà ¯Ã‚ ¬Ã‚ cient à ¯Ã‚ ¬Ã¢â‚¬Å¡exibility. Several processing element consumes more power, so by using FTA the PE can be reused and power is reduced. Fig 2. Folding Architecture In folding architecture, we can reuse the PEs with the help of counter and FSM. Iteration count in the counter contains the total number of times the specified PE going to be reused. The FSM enables and reset the iteration count based on the instructions. B. Parallel prefix adder. Adders are also very important component in digital systems because of their extensive use in other basic digital operations such as subtraction, multiplication and division. Hence, improving performance of the digital adder would greatly advance the execution of binary operations inside a circuit compromised of such blocks. The performance of a digital circuit block is gauged by analyzing its power dissipation, layout area and its operating speed. The main idea behind parallel prefix addition is an attempt to generate all incoming carries in parallel and avoid waiting until the correct carry propagates from the stage of the adder where it has been generated.Parallel prefix adders are constructed out of fundamental carry operators denoted by  ¢ as follows (G, P)  ¢ (G, P) = (G+G ·P, P ·P) where P and P indicate the propagations, G and G indicate the generations. The fundamental carry operator is represented as Figure Fig 3. Carry operator   Ã‚   A parallel prefix adder can be represented as a parallel prefix graph consisting of carry operator nodes. The parallel prefix Ladner Fischer adder structure has minimum logic depth, but has large fan-out requirement up to n/2. Ladner Fischer adder has less number of delay compared to other parallel prefix adders. Power Delay Product should be less inorder to achieve high throughput and speed. Fig 4. Ladner Fischer Parallel Prefix Adder The Ladner Fischer adder construct a circuit that computes the prefix sums in the circuit, each node performs an addition of two numbers. With their construction, one can choose a tradeoff between the circuit depth and the number of nodes. V CONCLUSION This paper presented the Folded Tree Architecture and Multi-Bit Flip-Flop Merging technique for WSN applications. The design describes many data processing algorithms for WSN applications along with parallel prefix operations and clock distribution networks. Power is saved using flip flop merging technique by providing single clock signal to mergeable flip flops with the help of combinational lookup table. Thus this technique can be effectively used for clock distribution in integrated circuits requiring low power consumption in clock distribution network and low skew clocks. Area is reduced using folded tree architecture by reusing processing element. Ladner Fischer parallel prefix adder reduces the delay constraints and achieve high throughput. The proposed architecture significantly reduces both power and area in WSN nodes, can save up to half of the power in total sensor node. REFERENCES V. Raghunathan, C. Schurgers, S. Park, and M. B. Srivastava, â€Å"Energy-aware wireless microsensor networks,† IEEE Signal Process.Mag., vol. 19, no. 2, pp. 40–50, Mar. 2002. C. Walravens and W. Dehaene, â€Å"Design of a low-energy data processing architecture for wsn nodes,† in Proc. Design, Automat. Test Eur. Conf. Exhibit., Mar. 2012, pp. 570–573. D. Duarte, V. Narayanan, and M. J. Irwin, â€Å"Impact of technology scaling in the clock power,† in Proc. IEEE VLSI Comput. Soc. Annu. Symp.,Pittsburgh, PA, Apr. 2002, pp. 52–57. H. Kawagachi and T. Sakurai, â€Å"A reduced clock-swing flip-flop (RCSFF)for 63% clock power reduction,† in VLSI Circuits Dig. Tech. Papers Symp., Jun. 1997, pp. 97–98. Y. Cheon, P.-H. Ho, A. B. Kahng, S. Reda, and Q. Wang, â€Å"Power- aware placement,† in Proc. Design Autom. Conf., Jun. 2005, pp. 795–800. Y.-T. Chang, C.-C. Hsu, P.-H. Lin, Y.-W. Tsai, and S.-F. Chen, â€Å"Post-placement power optimization with multi-bit flip-flops,† in Proc.IEEE/ACM Comput.-Aided Design Int. Conf., San Jose, CA, Nov. 2010,pp. 218–223. P. Sanders and J. Traff, â€Å"Parallel prefix (scan) algorithms for MPI,† in proc, Recent ADV. Parallel Virtual Mach Message Pass, Interf., 2006, pp.49-57. G. Blelloch, â€Å"Scans as primitive parallel operations,† IEEE Trans. Comput.,Vol.38, no 11, pp. 1526-1538, Nov. 1989. D. B. Hoang, N. Kamyabpour â€Å"An Energy Driven Architecture for Wireless Sensor Networks† International Conference on parallel and Distributed computing Applications and technologies., Dec 2012. Nazhandali, M. Minuth, and T. Austin, â€Å"SensBench:Toward an accurate evaluation of sensor network processors,†in Proc. IEEE Workload Characterizat. Symp., Oct. 2005. M. Hempstead, D. Brooks, and G. Wei,† An accelerator-based wireless sensor network processor in 130 nm cmos,† J, Emerg. Select. Topics Circuits Syst., vol. 1, no. 2, pp. 193-202, 2011. B. A. Warneke and K. S. J. Pister, â€Å"An ultra-low energy micro- controller for smart dust wireless sensor networks,† in Proc. IEEE Int.Solid-state circuits conf. Dig. Tech. Papers. Feb. 2004, pp. 316-317. M. Hempstead, M. Welsh, and D.Brooks,†Tinybench: The case for a standardized benchmark suite for TinyOS based wireless sensor network devices,† in Proc. IEEE 29th Local comout. Netw, conf., Nov.2004, pp. 585-586. O. Girard. (2010). â€Å"OpenMSP430 processor core, available at opencores.org,† [online]. Available: http://opencores.org/project, openmsp430. H. Stone, â€Å"Parallel processing with the perfect shuffle,† IEEE Trans. Comput., vol. 100, no.2, pp. 153-161, Feb. 1971. M. Hempstead, J. M. Lyons, D. Brooks, and G-Y. Wei,† Survey of hardware systems for wireless sensor networks,† J. Low Power Electron., vol.4, no. 1, pp. 11-29, 2008. C.C. Yu. Design of low-power double edge-triggered flip-flop circuit. In IEEE Conference on Industrial Electronics and Applications, pp. 2054-2057, 2007. M. Donno, A. Ivaldi, L. Benini, and E. Macii. Clock tree power optimization based on RTL clock-gating. In Design Automation Conference, pp. 622-627, 2003.

J. R. R. Tolkien :: essays research papers

John Ronald Reuel Tolkien, creator of a world. When someone who knows Tolkien is asked about his works, one thought comes to mind, Middle Earth. This was the playground in his mind that such vivid descriptions of fantasylands came from. It is the base of his most well known stories, where dreams are just the norm. J.R.R. may owe much of his success to his diverse beginnings. On April 16, 1891, Mabel Suffield and Arthur Reuel Tolkien were married in Bloemfontein, South Africa. They soon gave birth to John Ronald Reuel Tolkien on January 3, 1892, who was christened later that month. In April of 1895 Mabel took J.R.R. and his younger brother to Birmingham England. Arthur, their father, was supposed to follow them in a few months, however never does, as he dies shortly before his trip. This causes a struggling early life for John, moving constantly. At age 7 he took the entrance exam for King Edwards School, failed, but gained acceptance a year later and move closer to the school. The Tolkiens move several more times, and end up near the Grammar School of St. Philips, where John’s mother enrolls him to save money. J.R.R. won a scholarship, however, and returned to King Edwards to continue his studies. On September 14, 1904, Mabel Tolkien, John’s mother, dies after a diabetic coma. After the death of his mother, the guardianship of his brother and him was taken over by Father Francis Xavier Morgan, a priest of the Birmingham Oratory. In 1908, J.R.R. started his first term at Oxford, and in 1915 he was awarded First Honours degree in English Language and Literature. The following year, March 22, 1916, John Tolkien married Edith Bratt. Between the years of 1917 and 1929, the couple had four children together, John, Michael, Christopher, and Priscilla. Tolkien’s children had a great impact on his writings. One of the best instances of this is in his book Roverandom. In 1925, while on vacation with his family on the Yorkshire coast, four-year-old Michael Tolkien lost his favorite toy, a little lead dog he was reluctant to put down even to play on the beach. To console and distract him J. R. R. improvised a story, the story of Rover, a real dog magically transformed into a toy. After many fantastic adventures in search of the wizard who wronged him, at last he wins back his doggy life.

Eugene Ionescos rhinoceros: True Means Resides In Action Not Words :: essays research papers

Eugene Ionesco's "Rhinoceros": True Means Resides in Action not Words I awoke sweating. Breathing heavily, I glanced over at my clock and read the time. 4:00 AM. I wasn't sure if this was reality or not so I ran my palm over my scalp. No bump. A sigh of relief came over me. "Phew," I said, "it was only a dream." This is a dream I have had often throughout the past couple of years. Each time, the bump in my dream gets bigger and bigger and each time I wake up I'm more and more frightened that the dream was real. "I will not be a rhinoceros," I tell myself over and over. "I will not." These words I tell myself are nearly meaningless though. They are words and nothing more. Futile attempts to ease the pain of my "rhinocerotic" life. The only way to really not become a rhinoceros is by making the existential decision not to do so. A main theme in Eugene Ionesco's, Rhinoceros, is that true meaning resides in action rather than in mere words. A resistance to taking action then results in one's becoming a rhinoceros. Jean illustrates this in the beginning of Act 2, scene 2, when we see Jean and Berenger bickering. Berenger feels that Jean isn't looking or feeling well and threatens to get him a doctor. Jean resists by saying, "You're not going to get the doctor because I don't want the doctor. I can look after myself." (pp. 62) This refusal comes from his arrogant view of himself as a "Master of [his] own thoughts," (pp. 61) and "[Having] will-power!" (pp. 7) By seeing the doctor, Jean would have put himself in the position of taking responsibility for his actions and seeing that he wasn't always the "master of his own thoughts" and that his will-power was actually quite weak. It would be admitting the meaninglessness in his futile attempts to remain a human. He didn't want to see that he, in fact, was becoming a rhinoceros. Had Jean agreed to see a doctor, he may have been saved. By seeing the doctor, Jean would have come to terms with his becoming a rhinoceros. After coming to terms with his current state, he could then change his subsequent state to one of taking action to be an individual. Berenger, however, illustrates the power in making an existential decision. The trumpeting call of the rhinoceros was a persuasive one, but Berenger was able to resist it through his commitment and determination. In the beginning of Act 3, Berenger and Dudard are speaking after Berenger was awakened

The Unspoken Dangers of Tanning Beds Essays -- Expository Essays Resea

The Unspoken Dangers of Tanning Beds Tanning beds are devices that emit ultraviolet radiation (UV rays) in order to darken one’s skin complexion. It is believed that approximately 28 million Americans are tanning indoors, in some 25,000 tanning salons nationwide (http://www.fda.gov/ cdrh/consumer/tanning.html ). The rising popularity of tanning beds came about a few decades ago when the media and society started emphasizing that bronzed skin was â€Å"in.† A variety of people use tanning beds, both men and women, and for a variety of reasons; some use them as a weekly (or even daily) routine, others use them seasonally (when it’s hard to get a tan in the winter) and then of course there are the â€Å"event† tanners who go before a big event like a prom, wedding or spring break cruise. Media and what it implies about today’s culture has a massive pull factor on what American people buy. Also, the effects of peer pressure cause people to tan in tanning beds; if the majority of your peers are doing it, then you don’t want to be the only pale kid on the block, despite the consequ...

Revenue-Recognition Problems in the Communications Equipment Industry Essay

1) In late 2000, Lucent announced that revenues would be adjusted downwards by $679m as a result of revenue recognition problems. Yet the firm’s market capitalization plummeted by $24.7bn. Why do you think the market reacted so negatively to Lucent’s announcements of the problems? The large drop in market capitalization is probably due to several factors. Historically, Lucent had successfully met analysts’ projections for 15 consecutive quarters before announcing, in January 2000, a major shortfall in profits relative to previous expectations. In June, the quarterly balance sheet reported an operating loss of $301m (for the first time since 1998) while warning of weaker profits in Q4. In addition, the revenue recognition issues announced by the new CEO appointed in October were surely perceived as an indication that Lucent’s management was managing revenues and therefore a possible cause of a future fall in revenues. This led investors to modify their earnings expectations in light of the revenue-recognition problems faced by the firm. Since a company’s share price reflects forecasts of future cash flows, and Lucent’s Q3 and Q4 revenues were substantially written-down, investors would rationally expect future earnings to be affected as well. In an efficient market environment, the $24.7bn in lost market capitalization would equal the discounted value of these expected cash flows. However, it is also likely that the repeated missed expectations caused an overreaction by investors, as the company was forced to revise its revenues downward two times over the span of two quarters. This probably raised fears in the market of more widespread problems with the firm’s accounting practices. It should also be kept in mind that the Internet bubble had just burst and a technology related company announcing an operating loss and lower revenues could easily cause a panic selloff among investors, as typically happens when a speculative bubble bursts. 2) What are the specific revenue recognition problems faced by Lucent? On December 22, 2000, Lucent announced a $679m downward adjustment in revenues  of their fourth-quarter financial statement from September 2000. There were four different reasons for the adjustment. First of all, Lucent stated $125m of recorded sales that did not meet the company’s revenuerecognition rules. These revenues were included in the financial statement due to â€Å"misleading documentation and incomplete communications between a sales team and the financial organization†. Additionally, Lucent sold $452m worth of equipment to system integrators and distributors and recorded them as revenues. In fact, the products were not passed on to the customers, because of their weakened financial condition, and Lucent had already verbally agreed to take back the equipment. Therefore, the sales could not be accounted as revenues. Thirdly, sales teams had verbally offered credits to customers worth $74m and booked them as revenue in order to boost the fourth-quarter numbers. As the credits were meant for use at a later date without an actual sale of equipment taking place, these could not be accounted as revenues in the fourth-quarter. Finally, sold equipment worth $28m had not been completely shipped, leaving the service incomplete. Since this violated the first revenue recognition criteria â€Å"The firm has performed all the services or conveyed the asset to the buyer†, recognition of these revenues is not in line with regulation. 3) What financial statement adjustments will Lucent have to make to correct the revenue recognition problems announced in late 2000? In our treatment of the accounting figures we found it necessary to make assumptions relating to tax rates and COGS, as the information is not given directly. In deciding which tax rate to use for the adjustments we have two obvious alternatives; either assume a corporate tax rate of 35%, or calculate the average tax rate based on the presented financial statement. However, due to certain revenues and expenses being non-taxable we have opted to discard the average tax rate as a suitable estimate, and assumed a corporate tax rate of 35%. In relation to the Cost of Goods Sold, Lucent faces the problem that some of  their goods are tangible (communications equipment) while some are intangible (software licenses, services etc.). We are aware of the fact that Lucent’s intangible assets are subject to different costs as its tangible assets, and therefore have to be restated differently. However, we do not know the costs of neither intangible nor tangible assets due to a lack of information and thus assume a representative cost mix that is proportional to total revenues. Hence, we use the average COGS (69% of revenues in Q4, 2000) when we calculate the restatements. In the balance sheet, we treat the physical goods as â€Å"inventory†, and intangible goods as â€Å"other current assets†. When readjusting the income statement and balance sheets we need to reduce the revenues by a total of $679mn, with a corresponding reduction in accounts receivable. The cost of goods sold is reduced by $470mn, as per our assumption above relating to the average cost of goods sold. On the balance sheet this is reflected in the increase of inventories for tangible sales, and other current assets for intangible sales. This leads to a reduction of pretax income of $209mn, and subsequently a reduction in income taxes of $73mn. In the balance sheet this is represented by a reduction in the deferred tax liability (current liabilities in Lucent’s balance sheet), and finally a reduction in stockholders retained equity by $136mn. 4) How would you judge whether a firm is likely to face revenue recognition problems? Revenue-recognition problems in Lucent’s case emerge from mismanagement of the financial statements by all parties involved in compiling them. For instance, the initial $125 million adjustment was due to miscommunication between the sales team and the financial organization. The lack of a proper internal reporting organization or of efficient external auditors therefore is a sign of increased risk of revenue misrepresentation. It is also important to mention that the events described in the case occurred before the Sarbanes-Oxley Act was enacted. This means that, at the time, financial statements did not require a seal of approval from top management in order to be published. The fact that these reports were approved and published suggests awareness and involvement of the board of administrators in the revenue-recognition problems. Making CEOs accountable  for the financial statements was an important step toward prevention of unwanted accounting practices. From a broader perspective, companies are constantly subject to the need of reaching – and beating – the market’s profitability expectations. Missing these targets may result in a steep share price fall, especially considering the â€Å"herd mentality† that is prevalent during market bubbles. Investors will typically overreact at the first sign of negative news from a company, triggering sharp sell offs in stock, as was the case with Lucent, during the height of the dotcom bubble. Further revenue misrepresentation drivers we can deduce from Lucent’s case are: firstly, firms providing financing solutions to customers may fall into the temptation of using these tools in order to boost their quarterly revenues by granting credits to clients. In fact, computing Lucent’s Account Receivables / Turnover ratio, it is observable that average collection days increase substantially from 1998 (85 days) to 2000 (119 days). This means that Lucent was selling products extending financing rather than collecting cash. Secondly, when companies rely on a distribution network rather than on direct sale it is easier for them to engineer revenue-boosting activities (e.g. provide distributors with more than what can be sold and take back the equipment later on). Thirdly, relying on big clients accounting for a large percentage of revenues increases may enhance corporate relationships, thus facilitating non-transparent verbal agreements or offbalance-sheet operations (e.g. financing, discounts). In addition, any changes in accounting practices and assumptions accounted for in the income statement should be investigated closer as a possible case of accounting fraud, as in the case of Lucent. In the 1st quarter of fiscal 1999 $1.3bn is booked as a â€Å"cumulative effect of accounting change†. This is enough to say that a revenue recognition problem exists, but certainly warrants further investigation. Finally, incentives of a more general nature to accounting malpractice include regular evaluation of company credit quality by rating agencies, and distorted compensation incentives for management. The former occur at regular intervals, providing incentives for management to â€Å"polish† a firm’s balance sheet prior to evaluations by the agencies, while the latter usually  involves stock options. Since employees are only allowed to sell their options at certain dates, they have an incentive to push the company’s share price up through accounting manipulation, prior to executing their options. 5) Assess whether any of Lucent’s competitors are likely to face revenue recognition problems in the coming quarters. Cisco Systems’ multichannel approach to sales and marketing includes a direct sales force to distributors, value-added resellers and system integrators. This could allow them to boost their revenues by selling excessive amounts to distributors close to the end of a quarter and taking the equipment back afterwards. On the other hand, Cisco does not rely on a single client, but has a diversified client base. In addition, the financing that Cisco provides is clearly reported on the balance sheet as noncurrent long-term lease receivables, which clearly differs to Lucent’s approach concerning verbal agreements about credits to clients. Unlike Cisco, Juniper Networks mainly relies on one large customer, WorldCom, who generated 18% of their revenues in 2000. Thus, they were highly dependent on that client and had most likely build up a close relationship with them, both concerning equipment sales and credit granting. This increases the risk of false revenue recognition due to either channel stuffing or the sale of equipment (meant to be taken back if not sold) close to the end of the quarter. Nortel is mainly a service provider, in fact 82% of its revenues are made up by services. This could be a red flag for revenue-recognition issues as services may have no clear delivery date and thus allow revenue management. In addition, Nortel granted credit to its customers of $5.6bn, of which only $1.5bn had been used. This could mean that Nortel is trying to attract customers by aggressively offering financing. On the other hand, Nortel does not depend on any single client. We did not find any significant pattern in insiders’ dispositions of their stock options to indicate fraudulent activity, neither for Lucent or any of their competitors. We also closely examined the two key ratios â€Å"Account Receivables Turnover† and â€Å"Cash Flow Return† for Lucent and its competitors (Juniper Networks has been excluded due to data absence). As can be seen in  the following graph all cash flow returns recently started to decline, which could raise concerns with regards to their revenue recognition policy. In Cisco’s and Nortel’s case one can see that this change is due to a parallel decline in cash flow from operations as well as an increase in sales. However, this movement by itself is not a red flag and could be due to other factors, which calls for a more detailed investigation. We can see that the suspicious decrease in cash flow return is mainly due to a substantial increase in sales and can also be seen in a substantial increase in accounts receivables. Hence, we looked at â€Å"accounts receivable turnover† or more precisely â€Å"days sales outstanding† and found that the average level over the course of the previous three years stays approximately the same while showing a negative trend for Cisco and even constantly decreased slightly for Nortel. This is a very good sign and means that these two still manage to collect their receivables in a timely manner although sales increase rapidly. Cash Flow Returns should therefore stabilize again in the ne ar future. Lucent’s Account receivables turnover on the other hand, as already elaborated in the previous question, steeply increases. This may indicate Lucent was selling products by extending financing to customers rather than collecting cash since we cannot apply the same argumentation as for Cisco and Nortel in Lucent’s case.

Calpurnia Character Analysis

Calpurnia enters into the story very early on in To Kill a Mockingbird, and is an integral part in the story. She works for the Finch family as their cook and mother figure. We get a very clear picture of Calpurnia in Chapter One. â€Å"She was all angles and bones. † This suggests the maybe she doesn’t have much money to buy food or that she is older. It also shows that she is older because â€Å"She had been with us ever since Jem was born, and I had felt her tyrannical presence for as long as I could remember. She doesn’t take any nonsense from the fact that â€Å"Our battles were epic and one-sided. † That Calpurnia had been with the Finches since Jem’s birth suggests that she is part of the family. Atticus trusts her to take care of the children when he is gone. â€Å"But there came a day when Atticus told us he’d wear us out if we made any noise in the yard and commissioned Calpurnia to serve in his absence if she heard a sound out of us. † He trusts her to discipline the children â€Å"Her hand was as wide as bed slat and twice as hard. When Scout questions Walter’s eating habits at the table in Chapter Three, Calpurnia is the one to discipline her. She says â€Å"‘That boy’s yo’ comp’ny and if he wants to eat up the table cloth you let him, you hear? ’† Atticus trusts her to take care of the children properly. Calpurnia is like a surrogate mother to the children. For example, when Scout refuses to gargle after chewing the Double-Mint gum, Jem threatens her with â€Å"you don’t ’n’ I’ll tell Calpurnia on you! † As gruff as may come off, she really does love the children. When Scout starts going to school, Calpurnia softens up. ‘â€Å"I missed you today. ’† She sets the boundaries for the children. â€Å"Our summertime boundaries (within calling distance of Calpurnia) were Mrs. Henry Lafayette Dubose’s house and the Radley place three doors to the south. † Calpurnia really treats the children as if they were her own. Calpurnia is more educated than most African-American people in Maycomb. She taught Scout to write. â€Å"She would set me a writing task by scrawling the alphabet firmly across the top a tablet, then copying out a chapter of Bible beneath. If Scout copied it up to her standards, she was rewarded. That she did this shows she knew more than most black people would know in Maycomb and it is yet another example of her mothering Scout. Calpurnia speaks as well as any other white person in Maycomb, except when she is mad. As shown when she disciplines Scout for the dinner incident with Walter. â€Å"She was furious, and when she was furious Calpurnia’s grammar became erratic. When in tranquility, her grammar was as good as anybody’s in Maycomb. Atticus said Calpurnia had more education than colored folks† Calpurnia tries to show Scout and Jem that there is no difference between white and African-American people. â€Å"For Calpurnia rarely commented on the ways of white people. † Calpurnia speaks like any other person in Maycomb to show the children she is equal to the white people in town. She has manners that are as good as anyone else in town. When Scout questions Walter’s eating habits, Calpurnia shows good manners in telling Scout to allow Walter carry on and be polite.

Bridge Collapse in Minnesota

The collapse of bridge I-35W in Minnesota during the rush hour of August 1put tremendous pressure on the reliability and safety of our bridges nationwide. Countless investigations and precautionary measures were done to make all bridges pass standard procedures and render it safe for both the vehicles and passengers. At the same time it gave dent to our structural designers ability to come up with a truly sound structure and bridge design. In this research paper we will try to dwell into the process involving bridge design, the different design loads, proper bridge repair and the type of bridge design used by engineers on the I-35W.After the collapse, we shall also try to decipher the expert opinion on the real cause and give credence to their theory on the failure of the gusset plate. We will also discuss the implication of the collapse of the bridge to the engineering profession, particularly if the failure was caused by defective design theories. And lastly after all is said and d one, I will try to give my assessment on the matter based on the materials culled from the different websites of the Internet. The Design Process The design of a structure (buildings or bridges) follows a tedious and complex process.Bridges for example needs extra meticulous observation because it carries moving loads and design flaws could only be accurately gauged if the sequence is subjected to a computer generated simulated stress diagrams. In this way structural designers can pinpoint the areas within the structure that is most likely to suffer fracture in extreme cases of bridge overload (BridgeArt). In the case of Bridge I-35W in Minneapolis, the designer may have been correct in all his assumptions as guided by the Design Manual of the American Institute of Steel Construction (AISC).From the dead load to the perceived moving loads, to the snow load and impact loads and also the necessary factor of safety were all incorporated in his design observation. Proof of the matter is the said bridge continued to thrive since its erection in 1967 and only collapsed four decades later. What may have caused the collapse of the bridge? Serious design errors could not be faulted because it should have failed at the onset – when the bridge was first used by the commuting public. Certainly the culprit could be poor maintenance procedures or bridge repairs.The Bridge Repair Data gathered from MN-DOT reveals that the bridge underwent major deck paving in 1970 and 1990. This twin repairs has already added tremendous dead load to the structure. Prior to the collapse of the bridge another paving was underway and materials were stockpiled on the deck plus the various equipment doing the repair job (Obi-Akpere). The recent resurfacing of the bridge placed an additional deadweight to the structure, roughly about 300 tons and may have triggered the demise of bridge I-35W (Obi-Akpere).The Bridge Design Design Engineers from the University of Minnesota in its report, foun d the bridge to be a non-redundant structure – meaning that all structural components act together and if one member fails the entire structure would collapse. Besides, the arched structure rests on only four pylons and failure of one especially during tremors would be catastrophic (Week III). The bridge I-35W is a typical three span continuous deck truss with a jargon of steel members and with the roadway on top.To protect the bridge from lateral movement because of extreme temperature changes (expansion and contraction), bridge bearings were used to allow the structure free movement (Week III). The Investigation From the wreckage of the collapsed bridge, investigators found several fractured gusset plates. Calculations were made on the stress capacity of the gusset plates and were found to be way deficient and the loads applied on the bridge were over their design limit. But no design imperfections were observed on the structural members (Samuel).This goes to show that fail ure of the structure emanates from too thin gusset plates, which could have been a construction error rather than a design flaw. Common sense dictates that a gusset plate should not be lesser in cross sectional area to a particular member served. In this case if proper construction procedure could have been followed, then structural failure should have been evident in the structural members (Roy). Or structure failure could be manifested in the welded joints or on the construction rivets and bolts.But such is not the case, then blame should be shouldered by the contractor for possibly undertaking stringent cost cutting measures or on his failure to notify the design engineer of the undersized gusset plates. And the MN-DOT field engineers likewise for its failure to spot the defective components installed in the structure (Gilbert). Also inspections were made by MN-DOT personnel on the bridge, but sad to say that they were unable to spot the defective gusset plates.Any ocular inspect ion would be useless unless field engineers would dutifully check each structural member by using calipers, particularly the thickness of the structural members. All the data are feed to their computer design software and only then can they be certain about their structural assessment (ArtiFactor). Implication to Engineering The collapse of bridge I-35W is a slap to the engineering profession, because it will tend to show that structural designers failed to provide safety nets to our structures not only on bridges but also buildings.It will put into question and scrutiny the methods and theories put forth by icons of the industry. For over 100 years our structural designers have practiced the profession based on the tenets of the formulas perfected by pioneers of the profession and a miscue like the collapse of the bridge will render all of these to naught. This will have a global effect, because everybody will now put to test the safety of our structures. With a disaster of this ma gnitude, people will now question the relevance of our structural design principles.Have we really made an accurate engineering theory and formula that could be fundamentally applied to bridge design? Or do we need to further hone our skills in order to come up with a design principle that will truly address such structural deficiencies? Engineers will now be irrelevant because what they have studied and practiced through the centuries will be rendered useless. It will be back to square one since all structures will now be deemed unfit for human habitation.What will now become of the human population – probably live in tents and simple lean-to structures? Development will be in a stand still as everybody will be wary of building structures, much more live in it. But initial finding from investigators is a breath of fresh air to structural designers. They only found errors in judgment in the use of materials and components not on the structural design. This will prove beyond d oubt that they have practiced sound design principles and that resulting structures are safer than ever. ConclusionIn the ensuing investigation, it is my opinion that what caused the collapse of bridge I-35W is not the design flaws (although evident) but the haphazard repair on the bridge made by personnel of the MN-DOT. Take note that resurfacing was made on the bridge for three occasions, one in 1970, 1990, and the one prior to the collapse of the bridge. Each time the bridge was resurfaced, almost 15,000 cubic feet of material was poured over it. This is only for the longest span of 458 feet and a width of 113 feet or roughly 8 road lanes, the one span directly over the river.This alone constitutes over 2,500 tons added to the original design load, and since this is done three times, the additional deadweight is tremendous. At the time of the incident equipment and materials were stockpiled making the structure grossly overloaded, no wonder the bridge collapsed (Week III). By the way repairs have been made on the bridge, it was actually an accident waiting to happen. It was never the fault of the structural designer, not even the contractor for he knew his responsibilities.But had they followed the steel design manual on gusset plate design, the structure could have survived the additional deadweight imposed on it. References American Institute of Steel Construction, Inc. 1967. Manual of Steel Construction. sixth ed. American Institute of Steel Construction: United States. Artifactor. â€Å"I-35W Bridge over Mississippi River collapsed! † Science Buzz. 2 August 2007. Science Museum of Minnesota. 4 February 2008. .BridgeArt. 2007. Long Tail Group. 4 February 2008. < http://www. bridgeart. net/software_database/>. Gilbert, Steve. â€Å"Design Flaw caused MN bridge collapse. † Sweetness and Light. 15 January 2008. 4 February 2008. < http://sweetness-light. com/archive/design-flaw-caused-mn-bridge-collapse>. Obi-Akpere. â€Å"The Critical Factor Why Minneapolis Bridge Collapsed. † NowPublic. 16 January 2008. 3 February 2008. < http://www. nowpublic. com/environment/critical-factor-why-minneapolis-bridge-collapsed>. Roy, Jennifer.â€Å"Design Flaw Identified in Minnesota Bridge Collapse. † Design News. 15 January 2008. 4 February 2008. < http://www. designnews. com/article/CA6522883. html>. Samuel, Peter. â€Å"MN/I-35W bridge collapsed because several gusset plates were grossly undersized – engineering error the cause. † TollRoadsnews. 15 January 2008. 3 February 2008. < http://www. tollroadsnews. com/node/3346>. Weeks III, John A. â€Å"Old I-35W Bridge. † John Weeks Homepage. 2005. 3 February 2008. < http://www. visi. com/~jweeks/bridges/pages/ms16. html>.