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UAV Coaxial Copter Uses Unique Drive Mechanism

Originally posted on Hackaday:

Personal UAV’s are becoming ubiquitous these days, but there is still much room for improvement. Researchers at [Modlab] understand this, and they’ve come up with a very unique method of controlling pitch, yaw, and roll for a coaxial ‘copter using only the two drive motors.

In order to control all of these variables with only two motors, you generally need a mechanism that adjusts the pitch of the propeller blades. Usually this is done by mounting a couple of tiny servos to the ‘copter. The servos are hooked up to the propellers with mechanical linkages so the pitch of the propellers can be adjusted on the fly. This works fine but it’s costly, complicated, and adds weight to the vehicle.

[Modlab’s] system does away with the linkages and extra servos. They are able to control the pitch of their propellers using just the two drive motors. The propellers are connected to the motors…

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The psalmist sa…

The psalmist says: “And all my desire is before you” (Ps 37[38],10). Not indeed before men, who cannot see into the heart: but “before you is all my desire”. Set your desire on him, and “the Father who sees in secret will repay you” (Mt 6,4). This very desire of yours is your prayer. If your desire is continual, your prayer is continual too. It was not for nothing that the Apostle Paul said: “Pray without ceasing” (1Thes 5 17). Was it so that we should be continuously on our knees, or prostrating our bodies or raising our hands that he says: “Pray without ceasing” ? If that is how we say our prayers, then my opinion is that we cannot do that without ceasing. But there is another and interior way of praying without ceasing, and that is the way of desire. Whatever else you are doing, if you long for that Sabbath rest, you are not ceasing to pray. If you do not want to cease praying, do not cease longing… You will lapse into silence if you lose your longing. Who did lapse into silence? Those of whom it was said: “Because wickedness is multiplied, the charity of many will grow cold” (Mt 24,12). The coldness of charity is the heart’s silence; its glowing ardour, the heart’s outcry. If charity “endures for ever” (1Cor 13,8), you are ever crying out; if always crying out, you are ever longing; if longing, you have not forgotten repose. ‘And all my desire is before you… And my groaning is not hidden from you”… If the desire is always within, so too is the groaning: it does not always come to the ears of men, but it is never absent from the ears of God.

The never old St. Augustin.

Never Understood This Myself

Why are we surprised to see this new holy Russia extend its protecting arm over the Christian-backed Ba’athist regime in Syria? Russian regimes have been staking a claim to guard that region’s Christians for 250 years.
-Philip Jenkins on CT

I am no huge fan of Russian imperialism, but I really don’t understand evangelical reactions to the Middle East and most foreign affairs. They always go for whatever is most damaging to local Christians.

As Kingfishers Catch Fire

As kingfishers catch fire, dragonflies draw flame;
As tumbled over rim in roundy wells
Stones ring; like each tucked string tells, each hung bell’s
Bow swung finds tongue to fling out broad its name;
Each mortal thing does one thing and the same:
Deals out that being indoors each one dwells;
Selves — goes itself; myself it speaks and spells,
Crying Whát I dó is me: for that I came.

I say móre: the just man justices;
Keeps grace: thát keeps all his goings graces;
Acts in God’s eye what in God’s eye he is —
Chríst — for Christ plays in ten thousand places,
Lovely in limbs, and lovely in eyes not his
To the Father through the features of men’s faces.
-Gerald Hopkins

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It’s practically impossible to build a mega-dam that will return its investment

marcy:

So maybe lets stop ruining ecosystems to build them?

Originally posted on Quartz:

The enormous hydropower dams springing up across the emerging world may simply be too expensive to ever yield real benefits to their builders, development economists warned today. One key reason why: Dam fans lying to themselves and others about how much the multi-billion dollar projects cost.

Between 2010 and 2035, demand for electricity will require worldwide power generation to increase from 5.2 terawatts to 9.3 terawatts, roughly equal to adding four times the electricity the United States currently generates. In emerging markets around the world, policymakers are responding with enormous dams—the Belo Monte in Brazil, the Diamer-Bhasha in Pakistan, the Jinsha river dams in China, the Myitsone in Myanmar, and the Gilgel Gibe III in Ethiopia—designed to create power and also shift enormous quantities of water.

But researchers at the University of Oxford, led by development experts Atif Ansar and Bent Flyvbjerg, built a database of 245 of the…

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