模拟测试卷4-2019-8月新卷 What did some members of the university planning committee initially oppose?

[00:00.00]Narrator:Listen to part of a lecture in an engineering class.[00:08.71]Professor:Let’s review the basics of what we covered on Friday. There’s only a limited supply of resources like oil and coal, but we’ll never run out of wind.[00:18.96] It’s abundant and there’s so much potential associated with this resource. It’s an environmentally friendly way to generate electricity. [00:29.14]So harnessing wind energy is being touted as a direction we need to be heading in to satisfy our future global energy needs.[00:39.73] And we look in depth at the standard model for harnessing wind energy: propeller wind turbines. Here’s the drawing of a propeller wind turbine again. [00:50.77]Now, as I mentioned Friday, nearly all wind forms use this type of turbine. You can’t really miss that distinct re-propeller design, but today I want to present an alternative type: the vertical axis wind turbine.[01:08.12] So, here’s a vertical axis wind turbine. Now, if you’ve seen one propeller turbine, you’ve basically seen them all. But with vertical axis turbines, there’s a huge variety in design and I chose to start with this particular model for a reason.[01:25.90] Cruz will be installing this in the ground in the architecture hall. We’ll be putting 40 of them at different heights starting today.[01:33.74] When they’re all up, the electricity they generate will power up more than 50% of the exterior satellites on our campus. [01:42.89]Now, my engineering department colleagues and I found that some members of the university planning committee were opposed to the installation idea, at least initially. [01:55.18]One of their big concerns was that it would negatively impact the aesthetics of the campus. However, once this particular model was officially presented, those members quickly came around to share our point of view. [02:09.10]To me, this particular model looks more like moving sculpture than a piece of eyesore. Its design blends well with the surrounding landscape and architecture.[02:20.34] Some other models definitely weren’t attractive. Anyway, once they go up and you’ve seen them, I’d be interested to see what you think. [02:30.23]But this wouldn’t be the engineering department if all we did was consider the aesthetics of technology. So, both vertical axis and propeller turbines will work fine with mid-range winds.[02:43.36] But one feature that makes any model of vertical axis turbine preferable to the propeller turbine is its ability to function in a wide range of wind conditions.[02:55.15] It can generate electricity by efficiently capturing low speed winds, say near 12 miles per hour. It also operates well in turbulent dusty winds, storm force winds.[03:08.65] Propeller turbines just can’t efficiently handle winds on these two opposite ends of the spectrum. And you know, when we’re considering a residential or an urban setting, now let’s face it, space is usually at a premium. [03:23.96]It’s a valuable, limited commodity. Unfortunately though, when you have a group of propeller turbines on a wind farm, they undergo a decrease in power output the closer they’re placed to one another so they have to be spread out.[03:39.40] They require a substantial amount of space. [03:42.63]Vertical axis turbines, however, can be placed in close proximity to one another. Consequently, you can reduce the amount of land needed and fit more turbines on it. Ultimately then, they overcome the biggest constraint faced by wind farms. [03:59.71]Now, there’s a study. Well, strangely enough, we’re learning ways we might continue to increase the efficiency of turbines by observing schools of swimming fish.[04:11.25] See, when a fish moves its tail back and forth to achieve forward propulsion, it obviously moves the water around it back and forth. And this motion affects nearby fish.[04:24.05] And we’ve noticed that fish arrange themselves, they space themselves in relationship to one another to take advantage of the back and forth motion of the water caused by the others. [04:36.18]In other words, they arrange themselves in a strategic configuration which make the forward motion of the group most efficient. [04:44.85]Now, the fish study has provided insight into how a vertical axis turbine affects the air around it for nearby turbines. And the implication is that there could be a significant increase in efficiency if we change the way we set up wind farms.[05:03.35] Currently, wind farms are configured so that all turbines in the group rotate in the same direction. But what if we set up vertical axis turbines in alternating rows?[05:14.92] I mean, so one row of turbines spins in one direction, then the next row spins in the opposite direction, so clockwise and then counterclockwise. This idea is now being tested in the field.