stated preference和revealed preference有什么区别
时间: 2023-04-09 15:01:42 浏览: 146
Stated preference和revealed preference是经济学中的两个概念。Stated preference是指人们在被问及偏好时所表达的意愿,而revealed preference则是指人们通过实际行为所表现出的偏好。两者的区别在于,stated preference是基于人们的主观意愿,而revealed preference则是基于人们的实际行为。因此,stated preference可能会受到人们的主观因素的影响,而revealed preference则更能反映人们的实际偏好。
相关问题
SMT32编成实现D1和D2两个LED的交替闪烁控制,闪烁频率以能看清为准
您好!可以使用STM32的定时器和GPIO模块来实现D1和D2两个LED的交替闪烁控制。以下是一个简单的示例代码:
首先,在STM32的CubeMX中开启GPIO和定时器模块,并将D1和D2的引脚配置为输出模式。
然后,在代码中初始化定时器和GPIO模块,并编写一个中断函数,在其中切换D1和D2的状态。
示例代码如下:
```c
#include "stm32f1xx_hal.h"
TIM_HandleTypeDef htim2;
GPIO_InitTypeDef GPIO_InitStruct;
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM2_Init(void);
int main(void)
{
HAL_Init();
SystemClock_Config();
MX_GPIO_Init();
MX_TIM2_Init();
HAL_TIM_Base_Start_IT(&htim2);
while (1)
{
}
}
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
if (htim->Instance == TIM2)
{
GPIO_PinState stateD1 = HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_0);
GPIO_PinState stateD2 = HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_1);
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, !stateD1);
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, !stateD2);
}
}
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct;
RCC_ClkInitTypeDef RCC_ClkInitStruct;
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
{
Error_Handler();
}
}
static void MX_TIM2_Init(void)
{
TIM_ClockConfigTypeDef sClockSourceConfig;
TIM_MasterConfigTypeDef sMasterConfig;
htim2.Instance = TIM2;
htim2.Init.Prescaler = 7200 - 1; // 10kHz frequency
htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
htim2.Init.Period = 5000 - 1; // 2Hz frequency
htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
if (HAL_TIM_Base_Init(&htim2) != HAL_OK)
{
Error_Handler();
}
sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
if (HAL_TIM_ConfigClockSource(&htim2, &sClockSourceConfig) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
}
static void MX_GPIO_Init(void)
{
__HAL_RCC_GPIOA_CLK_ENABLE();
GPIO_InitStruct.Pin = GPIO_PIN_0 | GPIO_PIN_1;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
}
```
在上述代码中,我们使用了TIM2定时器来产生中断事件,并在中断处理函数中交替切换D1和D2的状态。TIM2的频率为10kHz,周期为5000,因此闪烁频率约为2Hz。
同时,为了保证能够看清LED的闪烁,我们可以调整TIM2的周期,使得闪烁频率更加合适。
Develop and analyze a mathematical model that will assist negotiators to respond to a fixed set of water supply and demand conditions. Use the model to inform dam operations: When the water level in Lake Mead is M and the water level in Lake Powell is P, how much water should be drawn from each lake to meet stated demands? If no additional water is supplied (from rainfall, etc.), and considering the demands as fixed, how long will it take before the demands are not met? How much additional water must be supplied over time to ensure that these fixed demands are met?
Mathematical models can be useful tools in analyzing water supply and demand conditions and making decisions about dam operations. One approach to modeling this situation is to use a linear programming model that maximizes the amount of water supplied while meeting the fixed demand constraints. The objective function is to maximize the total amount of water supplied, and the constraints are the demand requirements and the availability of water in Lake Mead and Lake Powell.
Given the water level in Lake Mead (M) and Lake Powell (P), let x and y be the amounts of water drawn from Lake Mead and Lake Powell, respectively. The objective function can be written as:
Maximize: x + y
Subject to:
x + y >= D (where D is the total fixed demand for water)
x <= M (the amount of water available in Lake Mead)
y <= P (the amount of water available in Lake Powell)
x, y >= 0 (non-negativity constraints)
The solution to this linear programming model will give the optimal amounts of water to be drawn from each lake to meet the fixed demand.
If no additional water is supplied and the demands are fixed, it will take until the water in either Lake Mead or Lake Powell is depleted, or both, until the demands are not met. At that point, the optimization model will not have a feasible solution, and additional water must be supplied to meet the demand.
To determine the amount of additional water that must be supplied over time, the water levels in both lakes must be modeled over time, including inputs such as rainfall and evaporation. The model can then be used to determine the minimum amount of additional water that must be supplied each year to ensure that the fixed demands are met in the future.
This is just one possible approach to modeling this situation, and there may be other models that could also be used to assist negotiators in responding to water supply and demand conditions.