Switches and mortar in the Internet's shadow : a study of the effects of technology on competitive strategy for the Internet's landlords

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2000.Includes bibliographical references (leaves 132-138).Communications technology has experienced a period of explosive growth, driven by a confluence of legal, political and technical factors including the following: the 1968 Carter Phone and 1980's competitive carrier decisions, the 1984 divestiture of AT&T, the Telecommunications Act of 1996, the development and standardization of new technologies, and the proliferation of the Internet and World Wide Web. This thesis asks the fundamental questions: How has the rapid growth of the Internet and other communications technologies changed the competitive strategy of commercial tenants, and how have these changes affected commercial real estate developers? This study proposes that developers and landlords need to use more forward-looking theories of competitive strategy in order to understand the current and future real estate needs of technology-driven commercial tenants. Telecommunications deregulation and the growth of the Internet led to the creation of a new and rapidly growing high technology industry and commercial tenancy. Deregulation and the Internet also transformed the way traditional commercial real estate uses information technology, encouraged the forging of partnerships between commercial real estate professionals and "last mile" information technology contractors, and resulted in the creation of a new commercial real estate product-the telecom hotel.' Current literature suggests traditional commercial tenants might differ from Internet-based business tenants in four general areas of the development process: feasibility, site selection, design and building operations. The proliferation of the Internet as a catalyst for new real estate products, commercial tenants and partnerships, and the observed differences in development practices between traditional and commercial tenants are both clues to fundamental differences between these two tenants' competitive strategies. It is possible to understand these clues to tenant behavior by taking an in-depth look at how these two tenants compete in their respective industries. Traditional commercial business tenants appear to conform to Michael Porter's theories on competitive strategy and advantage. High-tech tenant's competitive strategies seem to be more accurately reflected by Gary Hamel and C.K. Prahalad's model of competition for the future. These two theories, and the industries they represent, differ in four dimensions: Future versus Past/Present orientation, technology use, rate of growth, and resource use. In comparing three case studies on these four strategic dimensions, this thesis concludes that Porter's more stable, efficiency-oriented model does explain the strategy of Northwestern Mutual, a large insurance organization. Hamel and Prahalad's model better explains the hectic, high growth, future orientation of Akamai and YankeeTek Incubator as well as Teleplace, a telecom hotel service company. Hamel and Prahalad and Porter's frameworks explain significant discrepancies between predicted development practices based on current industry thinking, and observed development practices based on these in depth case studies. This thesis thus verifies a need by real estate developers and landlords to use forward-looking theories of competitive strategy when examining the current and future needs of hightech tenants.by Geoffrey Morgan and Benjamin V.A. Pettigrew.S.M

A complete system for controlling and monitoring the timing of the LHCb experiment

The LHCb experiment at CERN will study the results of the production of B/antiB in the LHC accelerator mesons with the higher precision ever. It is vital that the experiment is able to record sub-detectors signals at the optimal detector efficiency, referring to the right collision occurring in the LHC ring, and that those signals are stable, clean and reliable. The solution is the development of a complete system to centrally time align and at the same time to monitor the timing of the whole experiment. An electronics custom-made acquisition board, called Beam Phase and Intensity Monitor (BPIM), has the main aim to monitor the beam processing a bipolar signal coming from a dedicated Beam Pick-Up detector, sitting along the LHC ring and whose signal is a clear representation of the bunches of protons. The BPIM is then able to integrate the intensity of the beam and at the same time to compare the phase of the bunch signal with the clock coming from the timing distribution system as well as the phase of the orbit signal with the signal generated from the first beam bunch. The principal applications of the BPIM are to determine the position of the orbit signal locally, to monitor bunch-by-bunch the clock phase with respect to the bunch passing through the detector, to have a clear structure of the beam injected, to determine the exact trigger conditions for sampling events in the detector, to determine the exact trigger conditions for significative events of not, checking whether the detector samples a bunch with protons (or lead ions) or an empty bunch, to produce an empty crossing veto for the sampled events whenever a bunch is absent in the expected location, to have a relative measure of the intensities of bunch, to have instantaneaous information about the presence/absence of beam, and, not less important, to search for ghost bunches. The board is paired with the RF2TTC system developed by the LHC group and whose aim is to control, clean, convert and transmit the bunch clock (~40 MHz) and the orbit clock (~11 KHz) to the the whole experiment. A complete user-friendly interface system, developed using the SCADA software PVSS II with the Distributed Information Management (DIM) system as communication protocol, allows to control and monitor real-time the available information

The Design of an IEEE 1588 End-to-End Transparent Ethernet Switch

In measurement and control systems there is often a need to synchronise distributed clocks. Traditionally, synchronisation has been achieved using a dedicated medium to convey time information, typically using the IRIG-B serial protocol. The precision time protocol (IEEE 1588) has been designed as an improvement to current methods of synchronisation within a distributed network of devices. IEEE 1588 is a message based protocol that can be implemented across packet based networks including, but not limited to, Ethernet. Standard Ethernet switches introduce a variable delay to packets that inhibits path delay measurements. Transparent switches have been introduced to measure and adjust for packet delay, thus removing the negative effects that these variations cause. This thesis describes the hardware and firmware design of an IEEE 1588 transparent end-to-end Ethernet switch for Tekron International Ltd based in Lower Hutt, New Zealand. This switch has the ability to monitor all Ethernet traffic, identify IEEE 1588 timing packets, measure the delay that these packets experience while passing through the switch, and account for this delay by adjusting a time-interval field of the packet as it is leaving the switch. This process takes place at the operational speed of the port, and without introducing significant delay. Time-interval measurements can be made using a high-precision timestamp unit with a resolution of 1 ns. The total jitter introduced by this measurement process is just 4.5 ns through a single switch

An integrated broadband concentration/distribution network for multimedia application compatible with the Hybrid Fiber-Coax (HFC) architecture.

by Ringo Wing-kwan Lam.Thesis (M.Phil.)--Chinese University of Hong Kong, 1995.Includes bibliographical references (leaves 83-[88] ).Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Multimedia Network Requirement --- p.2Chapter 1.2 --- 100-Mbps Network Proposal --- p.2Chapter 1.3 --- Broadband Network on HFC Architecture --- p.4Chapter 1.4 --- The BEBP MAC Protocol --- p.5Chapter 1.5 --- Scope of the Thesis --- p.5Chapter 2 --- The MAC Protocol --- p.7Chapter 2.1 --- Fast Polling Protocol --- p.9Chapter 2.1.1 --- Round Robin Polling --- p.10Chapter 2.1.2 --- Binary Exponential Backoff Polling --- p.11Chapter 2.2 --- Protocol Design --- p.13Chapter 2.2.1 --- Lessons learnt from IEEE 802 LAN and Ethernet --- p.15Chapter 2.2.2 --- Protocol Data Unit --- p.17Chapter 3 --- Performance Analysis --- p.19Chapter 3.1 --- The Simulation --- p.19Chapter 3.2 --- Round Robin vs. BEBP --- p.24Chapter 3.3 --- Size of BEBP Network --- p.30Chapter 3.4 --- BEBP with Different Tx FIFO Size --- p.31Chapter 3.5 --- Limitation of the Host Bus Transfer Rate --- p.32Chapter 3.6 --- Performance with Different Packet Size --- p.36Chapter 4 --- Network Architecture --- p.40Chapter 4.1 --- Dual Bus Network Architecture --- p.40Chapter 4.2 --- Star Network Architecture --- p.41Chapter 4.3 --- Compatibility with Existing Networks --- p.42Chapter 4.3.1 --- Compatibility with 10BaseT UTP Star Network --- p.42Chapter 4.3.2 --- Compatibility with 10Base2 Coax Bus Network --- p.44Chapter 4.3.3 --- Compatibility with the HFC Coax Tree Network --- p.47Chapter 5 --- Implementation --- p.50Chapter 5.1 --- Physical Layer --- p.50Chapter 5.2 --- MAC Layer --- p.52Chapter 5.2.1 --- Continuous Mode Datalink --- p.53Chapter 5.2.2 --- Burst Mode Datalink --- p.53Chapter 5.2.3 --- The 9-bit Polling Commands --- p.54Chapter 5.3 --- Design of the NIC --- p.56Chapter 5.3.1 --- Transmitter Modules --- p.59Chapter 5.3.2 --- Receiver Module --- p.61Chapter 5.3.3 --- Serial Interface --- p.63Chapter 5.4 --- Design of the Hub/Router --- p.67Chapter 5.4.1 --- CUMLAUDE NET --- p.67Chapter 5.4.2 --- Hub/Router --- p.69Chapter 5.4.3 --- Concentrator --- p.72Chapter 5.5 --- Software - Device Driver --- p.73Chapter 5.6 --- Testing of NIC --- p.76Chapter 5.6.1 --- Packet Error Rate Testing --- p.77Chapter 5.6.2 --- UDP Transfer Rate Testing --- p.78Chapter 5.6.3 --- Other Applications --- p.79Chapter 6 --- Conclusion --- p.81Bibliography --- p.83Chapter A --- Abbreviation --- p.89Chapter B --- Simulation Source Code --- p.93Chapter C --- Simulation Results --- p.98Chapter D --- Circuit Diagram --- p.122Chapter D.l --- Network Interface Card --- p.123Chapter D.2 --- Router/Hub - Ring A Module --- p.123Chapter D.3 --- Router/Hub - Ring B Module --- p.123Chapter D.4 --- Router/Hub - Hub Module --- p.123Chapter D.5 --- Router/Hub - Power Module --- p.123Chapter D.6 --- Concentrator - Back Plate --- p.123Chapter D.7 --- Concentrator - Hub Connecting Module --- p.123Chapter D.8 --- Concentrator - Node Connecting Module --- p.123Chapter E --- PLD Source Code --- p.132Chapter E.1 --- GAL20V8 for NIC --- p.132Chapter E.2 --- Lattise ispLSI for NIC --- p.132Chapter E.3 --- GAL20V8 for Concentrator --- p.132Chapter F --- DSP Program --- p.140Chapter G --- Device Driver --- p.144Chapter G.1 --- The Network Driver : nic.c --- p.144Chapter G.2 --- The Header File : nic.h --- p.144Chapter H --- Testing Program --- p.151Chapter H.1 --- Packet Error Rate Testing Program --- p.151Chapter H.2 --- UDP Rate Testing Program --- p.151Chapter H.2.1 --- Datagram Client : dgcli.c --- p.151Chapter H.2.2 --- Datagram Server : dgecho.c --- p.151Chapter H.2.3 --- UDP Client : udpcli.c --- p.151Chapter H.2.4 --- UDP Server : udpserv.c --- p.151Chapter H.2.5 --- The Header File : inet.h --- p.15

Excited State Dynamics of Isolated Nucleobases and Base Pairs

Environmental conditions such as solar irradiation can induce biochemical reactions and pose a threat to organic molecules necessary in life. How DNA responds to radiation is relevant to human health because radiation damage can affect genetic propagation and lead to cancer. A detailed photochemistry is unraveled by studying the intrinsic properties of individual DNA/RNA building blocks, followed by extrapolation to larger systems such as base pairs via gas phase laser spectroscopy. Moreover, the photodynamics of nucleobases may further our understanding of prebiotic chemistry and its role in developing life as we know it. Electronic structure and excited state dynamics of nucleobases and base pairs have been studied in the past; however, detailed spectroscopy has not been reported for all of them. Moreover, some nucleobase analogues were never studied in the gas phase. As a result, we attempt to build on what was previously established on nucleobases and base pairs and then take a step further to explore a nucleobase analogue. This work reports studies of electronic structure and excited state dynamics of biological molecules via resonance-enhanced multiphoton ionization in the gas phase. First, we measured well-resolved vibronic spectra of all the molecules we studied by resonant two-photon ionization. Then, we performed double-resonance spectroscopy to further elucidate the structure and excited state dynamics of the target molecules. Because biomolecules typically exist in several tautomeric forms which are isolated under gas phase jet-cooled conditions, we used UV-UV double resonance spectroscopy to determine the number of tautomers present and their origins. We used IR-UV double resonance spectroscopy to obtain tautomer-specific IR spectra. We measured excited state lifetimes of tautomer-selected nucleobases by nanosecond and picosecond pump-probe spectroscopy. Using these methods, we were able to draw a new picture for the dynamics of bare nucloebases thymine and uracil in the gas phase. In the gas phase jet expansion, both molecules were present in the keto form and exhibited long lived excited states. These long lived states have been implicated in the formation of DNA photolesions by causing the formation of a cyclobutane pyrimidine dimer, which can lead to cancers such as melanoma and carcinoma. We also determined that replacing the oxygen in guanine with sulfur results in drastically different dynamics due to the heavy atom effect. With the use of a free-electron laser, we were able to collect IR spectra for multiple base pairs in the far-IR region (<880 cm-1). Although the far IR region has been difficult to access both experimentally and computationally, we were able to structurally characterize the molecules with the help of Born–Oppenheimer Molecular Dynamics (BOMD). This far-IR region yields new information because it is characterized by large-scale delocalized vibrations that cannot be observed in the mid-IR region.Finally, we used R2PI in combination with supersonic jet cooling and mass spectrometry to examine archaeological samples. We studies organic residues within pottery sherds from Maya vessels (600−900 CE) and Mississippian vessels (1100−1200 CE), successfully detecting three molecular markers, caffeine, theobromine, and theophylline, associated with the use of cacao

Towards a distributed real-time system for future satellite applications

Thesis (MScEng)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: The Linux operating system and shared Ethernet are alternative technologies with the potential to reduce both the development time and costs of satellites as well as the supporting infrastructure. Modular satellites, ground stations and rapid proto typing testbeds also have a common requirement for distributed real-time computation. The identified technologies were investigated to determine whether this requirement could also be met. Various real-time extensions and modifications are currently available for the Linux operating system. A suitable open source real-time extension called Real-Time Application Interface (RTAI) was selected for the implementation of an experimental distributed real-time system. Experimental results showed that the RTAI operating system could deliver deterministic realtime performance, but only in the absence of non-real-time load. Shared Ethernet is currently the most popular and widely used commercial networking technology. However, Ethernet wasn't developed to provide real-time performance. Several methods have been proposed in literature to modify Ethernet for real-time communications. A token passing protocol was found to be an effective and least intrusive solution. The Real-Time Token (RTToken) protocol was designed to guarantee predictable network access to communicating real-time tasks. The protocol passes a token between nodes in a predetermined order and nodes are assigned fixed token holding times. Experimental results proved that the protocol offered predictable network access with bounded jitter. An experimental distributed real-time system was implemented, which included the extension of the RTAI operating system with the RTToken protocol, as a loadable kernel module. Real-time tasks communicated using connectionless Internet protocols. The Real-Time networking (RTnet) subsystem of RTAI supported these protocols. Under collision-free conditions consistent transmission delays with bounded jitter was measured. The integrated RTToken protocol provided guaranteed and bounded network access to communicating real-time tasks, with limit overheads. Tests exhibited errors in some of the RTAI functionality. Overall the investigated technologies showed promise in being able to meet the distributed real-time requirements of various applications, including those found in the satellite environment.AFRIKAANSE OPSOMMING: Die Linux bedryfstelsel en gedeelde Ethernet is geïdentifiseer as potensiële tegnologieë vir satelliet bedryf wat besparings in koste en vinniger ontwikkeling te weeg kan bring. Modulêr ontwerpte satelliete, grondstasies en ontwikkeling platforms het 'n gemeenskaplike behoefte vir verspreide intydse verwerking. Verskillende tegnologieë is ondersoek om te bepaal of aan die vereiste ook voldoen kan word. Verskeie intydse uitbreidings en modifikasies is huidiglik beskikbaar vir die Linux bedryfstelsel. Die "Real-Time Application Interface" (RTAI) bedryfstelsel is geïdentifiseer as 'n geskikte intydse uitbreiding vir die implementering van 'n eksperimentele verspreide intydse stelsel. Eksperimentele resultate het getoon dat die RTAI bedryfstelsel deterministies en intyds kan opereer, maar dan moet dit geskied in die afwesigheid van 'n nie-intydse verwerkingslas. Gedeelde Ethernet is 'n kommersiële network tegnologie wat tans algemeen beskikbaar is. Die tegnologie is egter nie ontwerp vir intydse uitvoering nie. Verskeie metodes is in die literatuur voorgestelom Ethernet te modifiseer vir intydse kommunikasie. Hierdie ondersoek het getoon dat 'n teken-aangee protokol die mees effektiewe oplossing is en waarvan die implementering min inbreuk maak. Die "Real-Time Token" (RTToken) protokol is ontwerp om voorspelbare netwerk toegang tot kommunikerende intydse take te verseker. Die protokol stuur 'n teken tussen nodusse in 'n voorafbepaalde volgorde. Nodusse word ook vaste teken hou-tye geallokeer. Eksperimentele resultate het aangedui dat die protokol deterministiese netwerk toegang kan verseker met begrensde variasies. 'n Eksperimentele verspreide intydse stelsel is geïmplementeer. Dit het ingesluit die uitbreiding van die RTAI bedryfstelsel met die RTToken protokol; verpak as 'n laaibare bedryfstelsel module. Intydse take kan kommunikeer met verbindinglose protokolle wat deur die "Real-Time networking" (RTnet) substelsel van RTAI ondersteun word. Onder ideale toestande is konstante transmissie vertragings met begrensde variasies gemeet. Die integrasie van die RTToken protokol het botsinglose netwerk toegang aan kommunikerende take verseker, met beperkte oorhoofse koste as teenprestasie. Eksperimente het enkele foute in die funksionaliteit van RTAI uitgewys. In die algemeen het die voorgestelde tegnologieë getoon dat dit potensiaal het vir verskeie verspreide intydse toepassings in toekomstige satelliet en ook ander omgewings

Investigation of Orthogonal Frequency Division Multiplexing Based Power Line Communication Systems

Power Line Communication (PLC) has the potential to become the preferred technique for providing broadband to homes and offices with the advantage of eliminating the need for new wiring infrastructure and reducing the cost. Power line grids, however, present a hostile channel for data communication, since the fundamental purpose of the power line channel was only the transmission of electric power at 50/60 Hz frequencies. The development of PLC systems for providing broadband applications requires an adequate knowledge of the power line channel characteristics. Various types of noise and multipath effects are some of the limitations for power line channels which need to be considered carefully in designing PLC systems. An effect of an impulsive noise characterized with short durations is identified as one of the major impairment in PLC system. Orthogonal Frequency Division Multiplexing (OFDM) technique is one of the modulation approaches which has been regarded as the modulation technique for PLC systems by most researchers in the field and is used in this research study work. This is because it provides high robustness against impulsive noise and minimizes the effects of multipath. In case of impulsive noise affecting the OFDM system, this effect is spread over multiple subcarriers due to Discrete Fourier Transform (DFT) at the receiver. Hence, each of the transmitted communication symbols is only affected by a fraction of the impulsive noise. In order to achieve reliable results for data transmission, a proper power line channel with various noise models must be used in the investigations. In this research study work, a multipath model which has been widely accepted by many researchers in the field and practically proven in the Tanzanian power line system is used as the model for the power line channel. The effects of different scenarios such as variations in direct path length, path number, branch length and load on the channel frequency response are investigated in this research work. Simulation results indicate the suitability of multi-carrier modulation technique such as an OFDM over the power line channels. To represent the actual noise scenario in the power line channel, an impulsive noise and background noise are classified as the two main noise sources. A Middleton class A noise is modelled as an impulsive noise, whereas the background noise is modelled as an Additive White Gaussian Noise (AWGN). The performance of PLC system based on OFDM is investigated under Middleton Class A and AWGN noise scenarios. It is observed that Bit Error Rate (BER) for the impulsive noise is higher than the background noise. Since channel coding can enhance the transmission in a communication system, Block code and convolutional codes have been studied in this research work. The hamming code chosen as a type of the block code, whereas the Trellis Coded Modulation (TCM) selected from the category of the convolutional channel codes and modelled in Matlab2013b. Although TCM code produces improvements in the Signal-to-Noise Ratio (SNR), they do not perform well with Middleton class A noise. A rectangular 16-QAM TCM based on OFDM provides better BER rate compared to the general TCM