Determination of power-factor and permittivity of insulating materials ( hartshorn ward method )
绝缘材料的功率因子与电容率的测定(哈特逊和瓦德法)
Superintendent david hartshorn , who heads the metropolitan police 's public order branch , told the guardian that middle-class individuals who would never have considered joining demonstrations may now seek to vent their anger through protests this year .
Hartshorn , who receives regular intelligence briefings on potential causes of civil unrest , said the mood at some demonstrations had changed recently , with activists increasingly " intent on coming on to the streets to create public disorder " .
