Lost at Sea: Introduction to Numerical Methods through Navigation

Excerpt: The ship, El Perdido, was damaged during a storm which knocked out its main and backup power generators. Before the backup generator failed, Captain Miguel Gomez sent a distress call and the crew have been able to keep El Perdido a oat, but the ship is adrift in the Pacific Ocean off the coast of California. Thankfully, a US Coast Guard rescue operation is underway after receiving the distress call. The Coast Guard has El Perdido\u27s last known position and has mapped out the surface water velocities in this area as slope fields for longitude (x) and latitude (y), which they have updated using historical data and estimated predictions. Since the search grid is small enough, this curved region on the surface of the earth is relatively at

NTP comparison process

The systems engineering process for the concept definition phase of the program involves requirements definition, system definition, and consistent concept definition. The requirements definition process involves obtaining a complete understanding of the system requirements based on customer needs, mission scenarios, and nuclear thermal propulsion (NTP) operating characteristics. A system functional analysis is performed to provide a comprehensive traceability and verification of top-level requirements down to detailed system specifications and provides significant insight into the measures of system effectiveness to be utilized in system evaluation. The second key element in the process is the definition of system concepts to meet the requirements. This part of the process involves engine system and reactor contractor teams to develop alternative NTP system concepts that can be evaluated against specific attributes, as well as a reference configuration against which to compare system benefits and merits. Quality function deployment (QFD), as an excellent tool within Total Quality Management (TQM) techniques, can provide the required structure and provide a link to the voice of the customer in establishing critical system qualities and their relationships. The third element of the process is the consistent performance comparison. The comparison process involves validating developed concept data and quantifying system merits through analysis, computer modeling, simulation, and rapid prototyping of the proposed high risk NTP subsystems. The maximum amount possible of quantitative data will be developed and/or validated to be utilized in the QFD evaluation matrix. If upon evaluation of a new concept or its associated subsystems determine to have substantial merit, those features will be incorporated into the reference configuration for subsequent system definition and comparison efforts

Systems overview

Charts and accompanying text are presented that provide a brief synopsis of the contracted efforts for FY-92 in assessing nuclear thermal propulsion requirements, concepts, and associated issues. The objective of the effort is to provide NASA LeRC with assistance in space nuclear propulsion system requirements management and public acceptance planning

Expendable launch vehicle transportation for the space station

Logistics transportation will be a critical element in determining the Space Station Freedom's level of productivity and possible evolutionary options. The current program utilizes the Space Shuttle as the only logistics support vehicle. Augmentation of the total transportation capability by expendable launch vehicles (ELVs) may be required to meet demanding requirements and provide for enhanced manifest flexibility. The total operational concept from ground operations to final return of support hardware or its disposal is required to determine the ELV's benefits and impacts to the Space Station Freedom program. The characteristics of potential medium and large class ELVs planned to be available in the mid-1990's (both U.S. and international partners' vehicles) indicate a significant range of possible transportation systems with varying degrees of operational support capabilities. The options available for development of a support infrastructure in terms of launch vehicles, logistics carriers, transfer vehicles, and return systems is discussed

Smart-Contract Enabled Blockchains for the Control of Supply Chain Order Variance

Conflicts between supply chain members emerge because individually strategic actions may not be jointly optimal. Efforts to forecast consumer demand represent a source of conflict. Coordination of forecasts require a powerful incentive alignment approach. This work proposes a smart-contract equipped consortium blockchain system that creates an incentive structure which makes coordination with respect to forecasts economically appealing to a retailer and supplier. Distortions of demand due to uncoordinated forecasting is captured by a bullwhip measure which factors both forecast error and variance. Cooperation under the system is shown to help minimize this bullwhip measure. New outcomes to supply chain participants that allow for a higher reward is provided by the system. Under a fixed payout structure, the system achieves credibility of continued cooperation thus promoting an optimal coordinated equilibrium between retailer and supplier. Blockchain technology represents a consensus formation mechanism which can intermediate the behavior of supply chain network

The Timing of Phage DNA Replication Influences Cellular Decision-Making

In this study, we use the bacteriophage lambda and E. coli model system to examine the effects of lambda DNA replication on the lysis-lysogeny decision. In the lytic pathway, lambda’s structural and lysis genes are rapidly transcribed and translated, culminating with the burst of the host cell and release of ~one hundred progeny virions which conduct further infection cycles. The temperate lysogenic pathway consists of the integration of the lambda genome into the host chromosome and the maintenance of stable, replicating lysogenic cells via the repression of lambda lysis and replication genes. We employ nalidixic acid (NA), a quinolone antibiotic, as an inhibitory agent to lambda DNA replication. NA inhibits DNA gyrase, leading to the buildup of positive supercoiling stress ahead of replication forks and a stall in DNA replication. Both E. coli and phage lambda rely on DNA gyrase for maintaining their respective DNA molecules in proper supercoiled states to facilitate DNA replication. In this work, we determine that a delay to the start of lambda DNA replication significantly affects decision-making in the lysis-lysogeny system and we discuss the mechanisms which could lead to the altered outcomes. We also examine an alternate method of altering lambda DNA replication by controlling the production of lambda-specific DNA replication proteins, a protein critical specifically for initiating the replication of lambda DNA molecules. By infecting cells which may be induced to express O or P with lambda mutants which are deficient for that protein, we could potentially observe variances in the lysis-lysogeny decision at distinct DNA replication rates