The Pricing of Customer Access in Telecommunications

Is the loop, which provides customers with access to the switchednetwork, a service in its own right, or is it purely an inputinto the production of the final service, which is usage ofthe switched network? Agreeing with Kahn and Taylor that thequestion of whether the loop is an economic good is irrelevantto the pricing issue, this paper goes on to claim that pricingat marginal cost is not an appropriate welfare maximizationrule due to network externalities that make the private benefitof access less than the social benefit. Socially efficient pricingis likely to involve pricing below the marginal cost of accessto some consumers and above the marginal cost of access to others.One implication is that a contribution to the local loop fromInterexchange Carriers (IXCs) or IXC customers may be optimal.     

A network analyzer-based tissue characterization system

A novel ultrasound tissue characterization system is described which utilizes a network analyzer, S-parameter test set, 180° hybrid junction, and a mock transducer circuit to exploit the wide-band potential of a commercial piezoelectric polymer transducer. The relatively short round-trip pulselength achieved using the system (70 ns in water) is compared to that obtained using a high-frequency pulser/receiver and the same transducer (130 ns in water). Finally, the in vitro acoustic response of a section of neonate porcine carotid artery obtained using the network analyzer-based system is reported, along with histologic results for the same vessel     

一种可用于可调谐环行Ti：Al_2O_3激光器的宽带单向器

本文介绍一种宽带单向器的原理及设计。选用ＴＧＧ作磁旋光介质，旋光石英晶片作补偿片，所设计的色散补偿型宽带单向器预计可在７００～１０００ｎｍ波长范围内实现环行激光腔中的单向行波运行；将其应用在可调谐环行Ｔｉ：Ａｌ２Ｏ３激光器中，获得了良好的实验结果。     

Water from the African sun

One of the world's most ambitious photovoltaic programs is pumping water from wells in the drought prone Sahel region. An important side benefit is an infrastructure trained in installing and maintaining the systems     

High-frequency ultrasonic cleaning tank utilizing oblique incidence

Transmission characteristics of a double-structured tank, used for high-frequency (1 MHz range) ultrasonic cleaning of semiconductor wafers and substrates, were improved by utilizing oblique incidence of ultrasonic waves. As the sound transmittivity through a plate in water varies with the angle of incidence, the bottom of the Pyrex glass inner container was slanted at the angle where strong transmission occurred. In the slant-bottom container, an intensive and uniform sound pressure distribution was measured with a polyvinylidene fluoride (PVDF) hydrophone probe. In comparison with the conventional horizontal-bottom container, it was shown that the distributions as well as amplitude of sound pressure were remarkably improved by slanting the bottom of the inner container at the proper angle     

Generalized impedance control of robot for assembly tasks requiringcompliant manipulation

To perform assembly tasks requiring compliant manipulation, the robot must follow a motion trajectory and exert an appropriate force profile while making compliant contact with a dynamic environment. For this purpose, a generalized impedance in the task space consisting of a second-order function relating the motion errors and interaction force errors is introduced such that the contact force can be commanded and controlled. With generalized impedance control, the robot can behave with a desired dynamic characteristic when it interacts with the environment. To ensure the success of the assembly, a strategy during task planning which takes into consideration the interrelation between motion and force trajectories as well as contact compliance is introduced. The generalized impedance control method is applied to the prismatic joint of a selective compliance assembly robot arm (SCARA) robot for inserting a printed circuit board (PCB) into an edge connector socket. Depending on the progress of the parts joining operation, various amount of interaction forces are generated which have to be accommodated. It is demonstrated that an assembly strategy which consists of a sequence of carefully planned target impedance can enable the task to be executed in a desirable manner. The effectiveness of this approach is illustrated through experiments by comparing the results with those obtained using a well-established position control scheme as well as the original impedance control method     

Theory of soliton stability in asynchronous modelocking

A new type of fiber laser modelocking is examined where a phase modulator is driven asynchronously with respect to a harmonic of the roundtrip cavity frequency. An asynchronous drive is able to produce high repetition rate (>1 GHz) soliton pulses that are shorter than the classic, active modelocking pulse width limit. It is shown that with a proper choice of fiber parameters, noise cleanup and soliton pulse shaping can be obtained using filtering and asynchronous phase modulation. Limits of asynchronous detuning are derived and a comparison with the parameters ranges for synchronous phase modulation is also presented