Time-Delay for Two-Compartment Models Used for Study of Enterohepatic Circulation of Drugs

A two-component model with time lag was proposed to describe pharmacokinetics of drugs subject to enterohepatic circulation. An analytic expansion of the amount of drug, at any time, in the central compartment after an intravenous bolus, or an oral intake, or a constant infusion, from a zero or nonzero equilibrium is given. By computer simulations, plasma level profiles are obtained and lead to rebounds and secondary peaks, according to experimental evidences.     

A Microprocessor Controller for a Personal Typewriter for Visually Handicapped Users

The design of a microprocessor controller for a personal typewriter for the visually handicapped is outlined. The controller is interfaced to an electronic or electronic-mechanical typewriter with a golf-ball or daisy-wheel print head, and uses the correcting feature to produce a personal typewriter for the visually handicapped; this enables, at minimal cost, the production by the visually handicapped user of typewritten text which is error-free and of good layout without the intervention of sighted help.     

Technical Preplanning for Litigation

Litigation strategies often depend upon decisions made during or prior to the start of design or development of a product The features of a liability prevention program are reviewed so that documents with the necessary technical content for successful defense of a litigation will be available if needed. Their development during the design, manufacturing, and marketing phases of a product's life can benefit product safety, quality, and cost.     

Electronic music synthesis for recordings

Electronic music synthesis is a process whereby several parts or elements of a musical composition that are performed or produced as separate entities are combined to form the entire or rendered composition. Since the entire process can seldom be carried out in real time, the synthesis of music has not been a performing-type rendition; therefore, the final product takes the form of a record that can be reproduced at any given time. Electronic music synthesis includes the modification and combination of conventional and original sound sources, manual and programmed electronic music synthesizers, and digital computers.     

Criteria for multichannel signal separation

We consider the problem in which we want to separate two (or more) signals that are coupled to each other through an unknown multiple-input-multiple-output linear system (channel). We prove that the signals can be decoupled, or separated, using only the condition that they are statistically independent, and find even weaker sufficient conditions involving their cross-polyspectra. By imposing these conditions on the reconstructed signals, we obtain a class of criteria for signal separation. These criteria are universal in the sense that they do not require any prior knowledge or information concerning The nature of the source signals. They may be communication signals, or speech signals, or any other 1-D or multidimensional signals (e.g., images). Computationally efficient algorithms for implementing the proposed criteria, that only involve the iterative solution to a linear least squares problem, are presented     

PCB阻焊膜下方线路腐蚀失效案例研究

近年来一些PCB组件在使用或储存一段时间后出现表面线路发黑甚至开路,导致产品失效。本文通过电路分析、电镜能谱、金相切片、离子色谱等一系列分析,确定失效为线路腐蚀所致,并分析了线路腐蚀的原因以及提出了解决方法。     

多种IC设计中Cu CMP阻挡层浆料选择和去除率的控制

集成电路的前缘技术是在低k介质材料上设计3个盖层的复杂结构,上面的盖层可以用TEOS(tetraethyl orthosilicate)四乙基原硅酸盐和/或氮化硅(SiN),下面的层可以在低k介质之上用氮碳化硅(SiCN),碳化硅(SiC),或CDO(carbon dopped oxide)直接生成。因此,对于适合铜CMP的选择性浆料,除了具备的高去除率之外,须是在去除上面盖层后能够在下面的介质层表面上终止的浆料。Rohm和Haas电子材料已经开发出能够有效地去除TaN,TEPS,SiN,CDO和/或SiCN,或这些材料的任一化合物的一系列浆料,或者是能够在TEOS、SiN、CDO、SiCN和SiC的任何一种或两种薄膜表面终止,这完全取决于这些特殊浆料的配方设计,通过一两种添加剂控制去除率达到要求。系列浆料中的大多数浆料研磨剂的含量较低,在低压力的情况下具有良好的去除率,为了适应多种行业的需求,高低pH值均可使用。大多数浆料是可调的,用一种或两种添加剂来控制薄膜的去除率。描述和讨论了这些浆料的改良原理。     

Methods for Calculating Distance Separation for Noninterfering Transmissions

Methods are presented for computing the distance required between transmitters with co-channel frequency assignments so that interference between them may be held below a specified level. Separate consideration is given to utilization probabilities resulting from communications traffic volume and to factors which are a function of the transmission medium and equipment characteristics. A graphical-analytic method is developed which reduces the usual path attenuation vs distance charts to normalized form. This permits rapid translation of the prescribed path attenuation into distance for any combination of antenna heights and wavelength in the line-of-sight region. The normalized charts also facilitate establishment of a probability, due to lobing, that path attenuation in a given region will be above or below a specified value when the transmitters or receivers are in motion. The basic methods are developed for distances well within the line-of-sight region, but special consideration also is given to distances near the horizon where the usual approximations do not apply.     

Education for innovation

Engineering education should encourage students to strive for a mastery of fundamentals and the cultivation of excellence?but this is not enough. Engineering education must be kept alive and relevant; and, to encourage creativity, it must stimulate the imaginations of students. The typical educational yard-stick of a student's performance, however, is the accuracy with which he can repeat, by rote, information obtained from a lecture or text. Original or unconventional approaches to problems are discouraged, and their proponents often penalized, thus discouraging and depressing the student. Must inventiveness be sacrificed to education?     

Caged ATP-fuel for bionanodevices

Micro- and nanodevices require the controlled delivery of energy to power a variety of processes. The current paradigm of connecting a miniaturized device to a set of macroscopic auxiliary devices, such as power supplies or pumps, for the delivery of electrical and mechanical energy needs to be replaced to enable the design of stand-alone integrated bionanodevices with applications in remote biosensing or nanomedicine. Biological nanomachines, such as the motor protein kinesin, can efficiently convert energy stored in chemical compounds, in particular adenosine 5'-triphosphate (ATP), into mechanical work. This ability is an attractive feature of hybrid devices powered by biomolecular motors, since it removes the need for the storage and conversion of electrical energy. The consequences are a simplified fabrication process and packaging, leading to higher yields and lower costs, and the broadening of the applications, which can now include field-deployable nanodevices. Here, the potential of caged ATP as fuel for such engineering applications is discussed. Caged ATP can be stored in the buffer solution of a bionanodevice, "uncaged" by UV light, and utilized as fuel by many enzymes to catalyze chemical changes or power active transport. We demonstrate that DMNPE-caged ATP can be stored in sufficient amounts in a typical device and that the activation can be triggered with a UV lamp or even sunlight.     

Three-dimensional multimodal image-guidance for neurosurgery

The authors address the use of multimodality imaging as an aid to the planning and guidance of neurosurgical procedures, and discuss the integration of anatomical (CT and MRI), vascular (DSA), and functional (PET) data for presentation to the surgeon during surgery. The authors' workstation is an enhancement of a commercially available system, and in addition to the guidance offered via a hand-held probe, it incorporates the use of multimodality imaging and adds enhanced realism to the surgeon through the use of a stereoscopic three-dimensional (3-D) image display. The probe may be visualized stereoscopically in single or multimodality images. The integration of multimodality data in this manner provides the surgeon with a complete overview of brain structures on which he is performing surgery, or through which he is passing probes or cannulas, enabling him to avoid critical vessels and/or structures of functional significance.     

A Device for Zero-Eye-Movement Reading

A portable personal computer has been programmed as a flexible and economical text display device capable of delivering single and multiple words or symbols flashed in the center of the screen with a wide range of repetition times and duty cycles (fraction of stimulus on/off time). All aspects of a computer-controlled experiment are controlled by a command file which can be created by workers with basic word processing skills and no knowledge of computer programming. Digital output is provided for recording stimulus timing on a chart recorder or computer for comparison to eye movements or other externally recorded variables. The system is ideal for zero-eye-movement reading experiments in which sentences are flashed a word or group of words at a time in the center of a CRT screen. If the subject is then asked to repeat the sentence aloud, the percentage of words correctly recalled is a measure of "reading comprehension." Results with nine subjects match previous data [1] obtained cinematographically.     

Pump source requirements for end-pumped lasers

A simple model is developed to relate laser design and properties of a gain medium to the requirements on a pump source for end-pumped lasers or amplifiers. A novel technique for scaling the pump power or energy for end-pumped lasers is presented and analyzed in terms of this model. The results indicate that power or energy scaling of the pump source for end-pumped lasers is not limited by geometry; however, the results also show that some minimum pump energy or power is required     

An Event-Structure Model for Communication

Floyd Allport's event-structure theory of behavior is the basis of this model. The process of communication is seen as the changing patterns of events or contacts between the constituent components of a transactional situation. A series of contacts between sub-components closes in on itself, thereby enabling the series to repeat itself and thus become a self sustaining process which can serve as a component of a higher order of a structure within the situation. This component may be the control cycle, or finally, the communication cycle. The analysis attempts to support George Gerbner's view that the behavioral patterns which sustain a message system are of more importance to research than whether a particular message does or does not change a specific response.     

Connectivity test for circuit detection

A new connectivity algorithm is proposed for testing whether a circ (a ring sum of two or more f-circuits) of a graph passes for a circuit or not, which is superior to the existing one. The labour involved in the proposed algorithm is proportional to n, as compared to the en of the old algorithm, where e and n represent the number of edges and nodes, respectively, of the graph.     

Statistical Methods for Vectorcardiographic Directions

Current statistical methods for treating vectorcardiographic directions are invalid because they treat the directions as points on a line or plane. It is more appropriate to consider the directions as points on a circle or sphere; the direction toward the center of gravity of such points is then a measure of the prevalent direction, and the distance from the center of the circle or sphere to the center of gravity is a measure of precision. The precision is a measure of how closely the directions cluster about the prevalent direction. The Fisher distribution is suggested as a probability model for spatial directions, and its usefulness is illustrated by 1) a test statistic for determining whether two samples of directions come from the same population, 2) the construction of a ``confidence circle' for the spatial prevalent direction, and 3) a method for obtaining planar prevalent directions and precisions from the spatial ones.     

Duality principle for asynchronous control circuits for directed graphs

The directed graph provides a means of analysing parallel computer structures, whether implemented in hardware or software. This letter discusses the asynchronous circuit modules used to implement the control section of such systems, and indicates a duality principle that permits a wider variety of control functions to be envisaged.     

Vision-in-the-loop for control in manufacturing

Machine vision is an invaluable component of automated manufacturing in situations where a high degree of randomness in the product, or the process, prevents the construction of a suitably structured environment for traditional automation or robotics. Case studies are presented of four mechatronic systems developed, or being researched, for quite different processes in the textile industry: garment assembly, lace cutting (scalloping), lace inspection and inkjet printing. They illustrate the potential for vision-in-the-loop in manufacturing. Although divergent in their purposes, the systems share a common theme: they each use line-scan machine vision, ‘incremental’ image processing rather than frame-based techniques and an integrated mechatronic design approach.