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The output power is always less than the input power The difference between the two is the amount of heat that will be generated due to electrical and frictional losses It is best to design and operate your robot in the highest efficiency range to minimize the motor heating If the motor is able to handle the heat build-up, it might be best to design the robot (or weapon) to be operated at a higher percentage of the motor s maximum power (to keep the motor as light as possible) For example, a motor that is used to recharge a spring-type weapon might be fine if operated at near-stall load for just a few seconds at a time The maximum amount of heat is generated when the motor is stalled A motor can tolerate this kind of heat for short periods of time only, and it will become permanently damaged if it s stalled for too long a period of time This heat is generated in the armature windings and the brushes, components that are hard to cool by conduction Figure 4-1 shows a typical motor performance chart These charts are usually obtained from the motor manufacturer, or a similar chart can be created if you know the motor constants The motor shown in Figure 4-1 is an 18-volt Johnson Electric motor model HC785LP-C07/8, which can be found in some cordless drills The constants for this motor are shown in Table 4-1 This motor is discussed here as an example motor to describe how all of the motor constants relate to each other and how they affect the motor performance Figure 4-1 graphically displays how the motor speed decreases as the motor torque increases and how the motor current increases as the applied torque on the motor increases For this particular motor, maximum efficiency is approximately.

This subject is covered in detail in 30 However, two points need to be made All of these packet switching systems suffer from highly variable interpacket delay The connection-less systems suffer from greater variability or are rather less predictable This arises from two sources First, the queuing and routing functions in the routers or packet switches, and second from the fact that the output port/path may be busy, requiring that the packet be queued until its turn arrives The systems we have discussed have no priority schemes for handling one type of packet ahead of any other In order to handle real-time applications, such as voice-over IP, we must be able to control interpacket delay and ideally control absolute end-to-end delay This is for all practical purposes impossible with the Internet as it stands since it is a CLNS and made up of many different providers The virtual, circuit-based networks have a better chance since there is a relationship between packet switches To these, we need only add the capability to evaluate the internal congestion and that of its external path to the next packet switch Then, during call setup, the packet switches could determine before setting up the virtual circuit whether it supports the delay or bandwidth requirements of the requestor

Figure 1-1

75 percent and it occurs when the motor is spinning at approximately 19,000 RPM Maximum output power from this motor occurs when the motor speed decreases to about 50 percent of its maximum speed and the current is approximately 50 percent of the stall current For all permanent magnet motors, maximum power occurs when 50 percent of the stall current is reached Motor manufacturers recommend that motors be run at maximum efficiency; otherwise, motors will overheat faster

Multi-protocol Label Switching is an attempt to Band-Aid virtual circuits onto a CLNS IP network The idea is to append a label (called also a tag, in which case it is refereed to as tag switching) to each packet Since we already discussed X25 and LCNs, this tag is essentially an LCN Thus, the routers can create a virtual circuit across the network We now have created an association between routers The routers can make a determination with their peers as to whether they have the capability to support the Quality of Servic e (QoS) requested at virtual circuit setup time This additional capability leads to multiple priority queuing systems inside the routers and packet switches Unfortunately, it can t address the in-and-out queuing times and the absolute transmission delay between packet handlers One way to address this problem is to employ an ATM network (see 11 )

People perform vastly different roles within organizations and therefore have varying needs for how and why they consume information It is important to understand these roles and the business reach and impact they have After identifying four roles of an organization, I will delve into the ways these roles can interact with data and why there is no one approach that satisfies all business needs The four roles that will be examined include Business Decision-Makers Knowledge Workers Analysts Line Workers Obviously, roles are not always so cut and dry, and one person may well have responsibilities in more than one role However, it is important to understand the business focus of each role and their corresponding need for information

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Summary