Distributed product and facility prototyping in extended manufacturing enterprises

In order to reduce the cost at the early product development stages, the planners need methodologies and tools that would allow them to judge upon the implications of the product design on the required manufacturing processes and facilities for their production. This paper reports on a new theoretical platform and a pilot implementation of a decision-making environment for distributed product and facility prototyping in an extended enterprise. The approach is based on an exchange of requests and information between collaborative autonomous agents that support the design, manufacturing planning and facility formation activities. The decision-making is formalized as iterative matching of design, process and facility attributes using multilevel resource capability representation within the extended enterprise. The system is implemented as an XML/CORBA-based environment for conveying design and manufacture messages across traditional technology boundaries. The reported research aims to provide the designers with a rapid manufacturing feasibility assessment tool to be used at different design and planning stages in extended manufacturing enterprises.     

Decomposition of singular large sparse matrix by adding dummy links and dummy degrees

Abstract

This paper proposes a simple scheme to decompose an n×n nonpositive definite matrix, A, associated with simultaneous equations, A X = B, into a triple‐factors (lower triangular, diagonal, and upper triangular matrices), i.e., Å = L D U, without interchanging rows or columns of A, but with A expanded with new rows and new columns to an m×m matrix Å. Whenever a near‐zero diagonal element, say ā_ii , is encountered and used as a pivoting element, an appropriate positive real number, say p, is added to this diagonal element, and a new term —px_k is also added to the i‐th equation, where x_k is a new variable called “dummy variable'’. If we also add a new equation —px_i + px_k = 0 to enforce the new added variable x_k equal to x_i then the modified i‐th equation has the same effect as the original equation. Therefore, the original solution X can be found directly from the expanded solution of the modified expanded equation. The method is very useful in solving the following problems: (1) nonlinear problems near the limit state, (2) postbuckling analysis, (3) system equations with constraint conditions, and (4) getting eigenvectors from eigenvalues.     

Time evolution of entanglement and bistability of two coupled quantum dots in a driven cavity

Abstract

The time evolution of entanglement between two quantum dots (QDs) trapped inside a cavity driven by a coherent quantized field is studied. In the presence of dissipation, entanglement shows many interesting features such as sudden death and revival, and finite steady state value after sudden death. We also investigate dependence of entanglement on dot variables and its relation to bistability. It is found that entanglement vanishes when the cavity field intensity approaches the upper branch of the bistability curve. When the cavity is driven by a modulated field in the presence of dissipation, it can periodically generate entanglement, which is much larger than the maximum value attained in the steady-state for this system but the dots are never fully entangled.     

Undrained Stability of Footings on Slopes

Solutions for the ultimate bearing capacity of footings on purely cohesive slopes are obtained by applying finite element upper and lower bound methods. In a footing-on-slope system, the ultimate bearing capacity of the footing may be governed by either foundation failure or global slope failure. The combination of these two factors makes the problem difficult to solve using traditional methods. The importance of a dimensionless strength ratio in determining the footing capacity is broadly discussed, and design charts are presented for a wide range of parameters. In addition, the effect of footing roughness and surface surcharge are briefly quantified.     

Impact of battery weight and charging patterns on the economic and environmental benefits of plug-in hybrid vehicles

Plug-in hybrid electric vehicle (PHEV) technology is receiving attention as an approach to reducing US dependency on foreign oil and greenhouse gas (GHG) emissions from the transportation sector. PHEVs require large batteries for energy storage, which affect vehicle cost, weight, and performance. We construct PHEV simulation models to account for the effects of additional batteries on fuel consumption, cost, and GHG emissions over a range of charging frequencies (distance traveled between charges). We find that when charged frequently, every 20 miles or less, using average US electricity, small-capacity PHEVs are less expensive and release fewer GHGs than hybrid electric vehicles (HEVs) or conventional vehicles. For moderate charging intervals of 20–100 miles, PHEVs release fewer GHGs, but HEVs have lower lifetime costs. High fuel prices, low-cost batteries, or high carbon taxes combined with low-carbon electricity generation would make small-capacity PHEVs cost competitive for a wide range of drivers. In contrast, increased battery specific energy or carbon taxes without decarbonization of the electricity grid would have limited impact. Large-capacity PHEVs sized for 40 or more miles of electric-only travel do not offer the lowest lifetime cost in any scenario, although they could minimize GHG emissions for some drivers and provide potential to shift air pollutant emissions away from population centers. The tradeoffs identified in this analysis can provide a space for vehicle manufacturers, policymakers, and the public to identify optimal decisions for PHEV design, policy and use. Given the alignment of economic, environmental, and national security objectives, policies aimed at putting PHEVs on the road will likely be most effective if they focus on adoption of small-capacity PHEVs by urban drivers who can charge frequently.     

Effect of barbituric acid on the self-polymerization reaction of bismaleimides

Barbituric acid (BTA) was used as an initiator for the homopolymerization of bismaleimide (BMI). The reaction was controlled by the amount of barbituric acid and ended up with solvent-soluble oligomers. The effects of varying the amounts of BTA, as well as the reaction time, on BMI's self-polymerization reaction were investigated. The thus-formed oligomers were characterized by gel permeation chromatography (GPC), infrared spectra (IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The degree of reaction increased proportionally to the concentration of BTA or the length of the reaction time. Thus, solvent-soluble BMI oligomer can be controlled and obtained.     

Multilevel multisensory-based security system for an intelligent home

This article describes a multilevel multisensor-based security system that has multiple interfaces to be applied in an intelligent home. The security system contains four levels. There is a passive detection level, an active detection level, a system supervising level, and a remote supervising level. The control unit of these passive modules is a HOLTEK microchip. Each passive module has two different interfaces (wireless RF and voice). These modules can use a voice to alarm users than an event has occurred, and can transmit the real-time status and image signal to the active detection level and the system’s supervising level via the wireless RF interface. The active detection level can communicate with other levels via the wireless RF interface or the wireless Internet. The remote supervising level, the supervising level, and the active detection level can communicate with other levels via the wireless Internet. The status of these modules can also be displayed on the monitor of the supervising computer. Finally, we present some experimental results using passive and active detection modules in the security system.     

Purification of C9 Arenes by Stripping Crystallization

A new separation technique called stripping crystallization (SC) is applied for purification of a mesitylene/pseudoumene mixture. SC combines distillation and crystallization to produce pure crystals due to the three‐phase equilibrium. The experiments demonstrate that a batch SC operation can purify pseudoumene from 85 % to 95 % for the pseudoumene‐rich mixture with a recovery rate of 51 % while it can only purify mesitylene from 85 % to 88 % for the mesitylene‐rich mixture with a recovery rate of 34 %. Compared to azeotropic distillation, SC is a clean separation technology as no chemicals are added. SC can be continued until the liquid phase is completely eliminated and only pure crystals remain in the feed. Compared to conventional crystallization, filtration or centrifugation is not needed to separate the solid crystals from the mother liquor since no mother liquor is present together with the crystals. In addition, crystal washing is not required since no impurities adhere to the crystal surfaces at the end of operation.     

Synthesis and properties of new water-soluble aliphatic hyperbranched poly(amido acids) with high pH-dependent photoluminescence

Water-soluble fluorescent hyperbranched poly(amido acids) (HBPAAs), based on wholly aliphatic structures were prepared through direct self-condensation of N-(3-aminopropyl) diethano succinate amine (APDESA, AB₂ monomer) in the presence of N,N-dicyclohexylcarbodiimide (DCC) as a condensation agent. The resulting HBPAAs were soluble in water, DMF and THF, and the structure of synthesized AB₂ monomer and polymers was confirmed by IR, ¹H, and ¹³C NMR measurements. TEM image indicated that the HBPAAs self-assembled in H₂O to form a spherical micelle with a diameter ranging from 30 to 50 nm. A significant pH-dependent profile of fluorescent intensity in the pH range from 3 to 10 was observed, wherein pH 4 provided a critical jump as the solution pH was increased. Further increasing the pH to 10 decreased the fluorescence because of partial hydrolysis. Strong fluorescence emission was observed at 395 nm in aqueous media and the fluorescence quantum yields are to 23%. These amphiphilic HBPAAs, with excellent water-solubility, void-rich space, multiple functional peripheries and high blue fluorescence, have potential uses as tracing nanocarriers and molecular-level containers.